Chapter One

#### The Meaning of Human Cloning: An Overview

The prospect of human cloning[^1] burst into the public consciousness in
1997, following the announcement of the successful cloning of Dolly the
sheep, and has since captured much attention and generated great debate,
both in the United States and around the world. Many are repelled by the
idea of producing children who would be genetically virtually identical
to pre-existing individuals, and believe such a practice unethical. But
some see in such cloning the possibility to do good for infertile
couples and others. Some want to outlaw it, and many nations have done
so. Others believe the benefits outweigh the risks and the moral
concerns, or they oppose legislative interference with science or
technology in the name of freedom and progress.

Complicating the national dialogue about human cloning is the isolation
in 1998 of human embryonic stem cells, which many scientists believe to
hold great promise for understanding and treating many chronic diseases
and conditions. Some scientists also believe that stem cells derived
from cloned human embryos, produced explicitly for such research, might
prove to be uniquely useful for studying many genetic diseases and
devising novel therapies. Public reaction to this prospect has been
mixed, with some Americans supporting it in the hope of advancing
biomedical research and helping the sick and the suffering, while others
are concerned about the instrumentalization or abuse of nascent human
life and the resulting danger of moral insensitivity and degradation.

In the United States, several attempts have been made to initiate a
comprehensive public review of the significance of human cloning and to
formulate appropriate policies. Most notably, the National Bioethics
Advisory Commission (NBAC) released a report on the subject of
cloning-to-produce-children in 1997.[^2] The Commission concluded that
cloning-to-produce-children was, at least for the time being, unethical
on safety grounds, and that the deeper and more permanent moral concerns
surrounding the practice should be the subject of continuing
deliberation "in order to further our understanding of the ethical and
social implications of this technology and to enable society to produce
appropriate long-term policies regarding this technology" (p. 106).

In this report, the President's Council on Bioethics takes up this
important charge, and considers the ethical and social implications of
human cloning (both for producing children and for biomedical research)
in their full scope, with the aim of informing public policy on the
matter.

Our work toward this end is guided by a number of explicit
methodological choices about modes of approach, points of departure, and
spirit of inquiry. We locate human cloning within its larger human and
technological context, rather than consider it in isolation. We focus
first on the broad human goods that it may serve or threaten, rather
than on the immediate impact of the technique itself. And we present the
strongest arguments for the relevant moral and policy positions, rather
than frame the arguments in order to seek consensus. By our broad
approach, our starting on the plane of human goods, and our open spirit
of inquiry, we hope to contribute to a richer and deeper understanding
of what human cloning entails, how we should think about it, and what we
should do about it.

Two points of clarification before we proceed. First, all of our
considerations and arguments assume that cloning techniques, both for
producing children and for biomedical research, could succeed in human
beings as they have with other mammals. Cloning-to-produce-children has
never been successfully carried out in humans, and cloning embryos for
biomedical research has not progressed beyond the earliest experiments.
We consider it part of our task to judge whether even attempts at human
cloning would be ethical or should be lawful. To conduct the analysis
and assessment needed for such judgment, we necessarily proceed on the
assumption, which we believe is supported by evidence from animal
experiments, that human cloning is indeed a possibility---that sooner or
later, if it were allowed and attempted, human cloning could be
successfully carried out. Practically all public discussion of the
ethics of human cloning has, whether expressly or not, proceeded on this
same premise, and rightly so.

Second, on some of the matters discussed in this report, Members of the
Council are not of one mind. Given that competing goods are at stake,
and different people regard them differently, this is not at all
surprising. Rather than bury these differences in search of a spurious
consensus, we have sought to present all views fairly and fully. Yet
transcending these differences is a more fundamental agreement about the
worthiness of the approach we have adopted and the arguments we have
made. Accordingly, the Council is unanimous in owning the entire report
and in recommending, to all, the report's discussions and arguments for
serious consideration.

In the remainder of this overview, we describe the context of human
cloning and the discussions it has generated. In the course of doing so,
we identify the kinds of questions and concerns that would permit a full
assessment of the meaning of human cloning. These questions and concerns
will guide us throughout the report.

***Human Cloning in Context***

It is useful to begin by observing how it is that the question of human
cloning has come before us. The prospect of cloning human beings
confronts us now not as the result of a strong public demand or a
long-standing need. Unlike sought-for medical therapies, it was not at
the outset pursued as a cure for disease. Neither has it been sought
explicitly as a tool for genetic control or "enhancement" of human
offspring. Cloning has arisen not so much because it was actively sought
for its own sake, but because it is a natural extension of certain
biotechnological advances of the past several decades.[^3]

For more than half a century, and at an accelerating pace, biomedical
scientists have been gaining wondrous new knowledge of the workings of
living beings, from small to great. Increasingly, they also are
providing precise and sophisticated knowledge of the workings of the
human body and mind. Such knowledge of how things work often leads to
new technological powers to control or alter these workings, powers
ordinarily sought in order to treat human disease and relieve suffering.

Questions regarding the meaning of acquiring such powers---both the
promise and the peril---have attracted scholarly and public attention.
For more than thirty years, ethical issues related to biomedical advance
have occupied the growing field of bioethics. Increasingly, these
ethical issues have spawned public discussion and debates. A growing
number of people sense that something new and momentous is happening;
that the accelerating waves of biotechnical advances touch deeply on our
most human concerns; and that the centuries-old project for human
mastery of nature may now be, so to speak, coming home, giving humanity
the power to alter and "master" itself.

One important aspect of human life already affected by new
biotechnologies is human reproduction. For several decades now, building
on advances in genetics, cell biology, and developmental biology, and on
technologies used first in animal husbandry, scientists around the world
have been adapting techniques and developing tools to study, influence,
and manipulate the origins of human life. Beginning with techniques of
artificial insemination and progressing through in vitro fertilization
(IVF) and intracytoplasmic sperm injection, artificial aids to
reproduction have come into standard medical use.

Cloning is, in one sense, another step along this path. It developed as
the result of research into mammalian reproduction and development,
where it is desired also as a means of replicating animals especially
useful to human beings. It is also proposed as an additional means to
overcome infertility in humans.

But the controversy surrounding human cloning, and the widespread sense
of disquiet and concern with which the prospect has been received around
the world, make it clear that cloning is not just another reproductive
technology, to be easily assimilated into ordinary life. Nearly all
participants in the public debate over human cloning appear to agree
that the subject touches upon some fundamental questions regarding the
nature of our humanity and the character of our society. In addition, it
raises questions about the aims of biomedical science and about the
relation between science and society, including the possibility and
desirability of exercising public control over the uses of biomedical
technology and the conduct of biomedical research. It is because we
sense these larger entailments that the subject of cloning matters so
much to us. It is these considerations that give the present debate its
force and prominence. Thus only through a serious reflection on these
broader questions can the full meaning of human cloning be discovered.
The prospect of human cloning may have been brought before us by the
march of biotechnology, but now that it is here it is incumbent upon us
to look well beyond its technical and medical aspects, if we are to
appreciate its significance in full.

Three areas of inquiry in particular seem essential to any understanding
of the full meaning of human cloning: the nature and meaning of human
procreation; the aims, ends, and means of biomedical science and
technology; and the relation of science and technology to the larger
society.

***Cloning and Human Procreation***

Human procreation provides the major context for considering the
prospect of cloning, especially cloning-to-produce-children. Much of the
time, most of us tend to take for granted this central aspect of human
life, through which all of us come to be and through which we give birth
to our posterity. But the prospect of creating children by cloning
brings this subject sharply before us and compels us to examine the
nature and meaning of human procreation. For
cloning-to-produce-children, while it may be a potential aid to human
reproduction, appears also to be a substitute for it, or at least for
its natural, un-programmed, sexual character. Properly to assess the
meaning of producing cloned children, one must first of all consider the
meaning of human procreation in all its aspects and entailments.[^4]

Human procreation, though seemingly an exclusively private act, has a
profoundly public meaning. It determines the relations between one
generation and the next, shapes identities, creates attachments, and
sets up responsibilities for the care and rearing of children (and the
care of aging parents or other needy kin). Thus, in considering
proposals to clone children, we must ask ourselves what cloning would
mean not only for the individual parents and children involved, but also
for the surrounding families and for all of society. Opinions on this
subject will of course differ, sometimes widely, as they rest on
possibly differing perceptions of human procreation and family life. Yet
the following basic observations, concerns, and questions seem
pertinent, notwithstanding possible differences of opinion among us
about how much weight to give them.

Among the important aspects of the topic are these: the meaning of
having children; the meaning of sexual, as opposed to asexual,
reproduction; the meaning of origins and genetic endowment for identity
and sense of self; the meaning of exercising greater human control over
the processes and "products" of human reproduction; and the difference
between begetting and making.

To understand what it would mean to clone a child, we do well to
consider most generally what it means to bring a child into the world,
and with what attitude we should regard his or her arrival and presence.
Our children are, to begin with, our replacements, those who will one
day stand in our place. They are, as Hans Jonas has remarked, "life's
own answer to mortality." Though their conception is the fruit of our
activity, and though we are responsible for saying "yes" to their
arrival, we do not, in normal procreation, command their conception,
control their makeup, or rule over their development and birth. They
are, in an important sense, "given" to us. Though they are *our*
children, they are not our *property*. Though they are our flesh and
blood, and deeply kin, they are also independent "strangers" who arrive
suddenly out of the darkness and whom we must struggle to get to know.
Though we may seek to have them for our own self-fulfillment, they exist
also and especially for their own sakes. Though we seek to educate them,
they are not like our other projects, determined strictly according to
our plans and serving only our desires.

If these observations are correct, certain things follow regarding the
attitudes we should have toward our children. We treat them rightly when
we treat them as gifts rather than as products, and when we treat them
as independent beings whom we are duty bound to protect and nurture
rather than as extensions of ourselves subject only to our wills and
whims. Might these attitudes toward children be altered by cloning, and,
if so, how? Would social attitudes toward children change, even if
cloning were not practiced widely? What might these changes mean?

To understand how the introduction of *a*sexual reproduction might
affect human life, we must first seek the intrinsic meaning of the
*sexual* character of human reproduction and what it implies for
individuals, for families, and for the relation between the generations.
Once again, the following observations---while hardly exhaustive---seem
pertinent and important.

In sexual reproduction,[^5] each child has two complementary biological
progenitors. Each child thus stems from and unites exactly two lineages,
lines that trace backward in similar branching fashion for ages.
Moreover, the precise genetic endowment of each child is determined by a
combination of nature and chance, not by human design: each human child
naturally acquires and shares the common human species genotype, each
child is genetically (equally) kin to each (both) parent(s), yet each
child is also genetically unique.[^6] Cloning-to-produce-children
departs from this pattern. A cloned child has unilineal, not bilineal,
descent; he or she is genetically kin to only one progenitor. What is
more, the genetic kinship is near-total: the cloned child is not
genetically unique, but shares almost completely the genetic endowment
of the "original" progenitor. Finally, this endowment comes to the
cloned child not by chance but by human choice and decision. What do
these differences mean for the cloned child, for family relations, and
for relations across the generations?

Origins and genetic endowment are significant aspects of who one is and
how one regards oneself, of one's "identity," individuality, and place
in the social order. The biological linkages and prospects implicit in
sexual reproduction help to define us, though, it should go without
saying, they do not define us completely. While we are more "what we
choose to become" than we are "where we came from," our human beginnings
matter, biologically, psychically, and socially. Because of the way we
are generated, each of us is at once (1) equally human, (2) equally
marked by and from birth as mortal, (3) equally enmeshed in a particular
familial nexus of origin, (4) equally individuated in our trajectory
from the beginning to the end of our lives---and, if all goes well, (5)
equally capable (despite our mortality) of participating with a
complementary other in the very same renewal of human possibility
through procreation. Our genetic identity---manifest, for instance, in
our distinctive appearance by which we are recognized by others and in
our immune system by which we maintain our integrity against "foreign
invasions"---also symbolizes and foreshadows exactly the unique,
never-to-be-repeated character of each human life. In addition, human
societies virtually everywhere have structured child-rearing
responsibilities and systems of identity and relationships on the bases
of these natural facts of begetting. Kinship is tied to origins, and
identity, at least in part, is tied to kinship. It is against this
background that we must consider the implications of clonal
reproduction, and the alterations it might produce in how cloned
children would regard themselves and how they would be regarded by
others. What would cloning-to-produce-children mean for individual
identity, for kinship, and for sense of self, not only for the cloned
child but also for his or her family?

Unaided sexual procreation is an activity at once natural, private,
mysterious, unmediated, unpredictable, and undesigned. With the arrival
of techniques such as IVF to assist procreation in the face of
infertility, the process becomes less private and more mediated. But
although technique is used, the basic structure of sexual
reproduction---the combination of genetic material from father and
mother resulting in a genetically unique child---is unaltered, the
outcome is still unpredictable, and the genetic endowment of the child
remains uncontrolled and undesigned. Cloning-to-produce-children would
seem to bring procreation under human control and direction. What would
this mean? What are the implications of allowing reproductive activities
to become increasingly technological and commercialized? Cloning would
be the first instance in which parents could select in advance the
precise (or nearly precise) genetic makeup of their child, by selecting
the donor to be cloned. It therefore forces us to ask what might be the
difference between begetting and making, to wonder whether cloning
somehow crosses the line between them, and, if so, to consider whether
and why that should worry us.

Though admittedly sketchy and incomplete, these preliminary reflections
on the nature and meaning of human procreation should enable us to see
cloning---and especially cloning-to-produce-children---in its most
important human context and to understand its deepest implications for
its practitioners and for society.

***Cloning and Biomedical Science***

Human procreation is not the only context for evaluating the prospect of
human cloning. As a product of biotechnology, a potential means of
assisted reproduction, and a possible source of cloned embryos for
research and medical use, human cloning also points us to questions
about the aims, ends, and means of biomedical science and technology.
Ordinarily, we are not prompted to much reflection about what science is
for and what goals technology should serve. Our society tacitly accepts
the self-directing and self-augmenting character of these activities,
and the vast majority of us support them because we esteem and benefit
from their contributions to human understanding and human welfare.
However, when developments such as cloning raise profound questions
affecting fundamental moral values and social institutions, we are
forced to consider the ends and means of science and technology, and to
explore their standing in the scheme of human goods.

To provide a context for assessing human cloning and its possible
benefits, we do well to remember the goals of medicine and modern
science: the great value and importance of treating disease and
relieving suffering, including the sorrows of infertility; and the great
value and importance of gaining knowledge about the workings of nature,
our own nature emphatically included. No one can doubt the merit of
these noble aims. Yet there has always been some disagreement about the
lengths to which we should allow ourselves to go in serving them.
Questions therefore arise about the need for limits on scientific
pursuits and technological activities, and, conversely, about the
meaning of such limits for the scientific and technological enterprises.

To address these questions, we must appreciate the human good of
biomedical science in its fullness, and we must ask about the necessary
and sufficient conditions for its flourishing. We must recognize, among
other things, the unpredictability of scientific discovery and
technological innovation, and the importance, therefore, of keeping open
lines of inquiry and experimentation regardless of current estimates of
their likelihood of success. Although serendipity often favors the
prepared mind, nature guards her secrets well, and even the best
scientists are regularly surprised by where the keys to the locks are
ultimately found.

But precisely because so much of biomedical science is exploratory and
experimental, scientific inquiry is not just thought but also action,
action often involving research on living subjects, including human
beings. And precisely because the use of technologies often has
unintended or undesirable side effects, affecting many human goods in
addition to health, safety, and the relief of suffering, large questions
are necessarily raised when the goods promoted by technology come into
conflict with others. For example, is the need to discover new cures for
the sick a moral imperative that should trump all other goods and
values? If not, then on what basis can it be limited? What moral
boundaries should scientists and technologists respect as they continue
their quests for knowledge and cures, whether or not they receive public
funding? How can society establish and enforce such boundaries? And, on
the other hand, how can science and technology be protected against
unreasonable limitations imposed by excessively fearful legislators or
overzealous regulators?

To be sure, these large questions are hard to answer in the abstract. As
a result, they do not recommend themselves for much deliberation. Yet
they are very close to the surface of the current debate about human
cloning. Moreover, implicit answers to these questions, seldom
articulated and rarely defended save by mere assertion, at least color
and may even determine what people think should be done about human
cloning. A clearer and more thoughtful awareness of the aims of
biomedical science could help us assess whether and how human cloning
might serve the ends of science and medicine and could help us more
fully consider its possible benefits and potential drawbacks.

But we must consider not only the ends of science, but also the means it
employs. Cloning, after all, is a technique, a means of reaching some
desired end. Even if the purposes it might serve are worthy, it must
still be evaluated as a means. Not every means employed in the pursuit
of worthy ends can pass ethical muster. This truth is widely recognized
in the establishment of canons of ethics regarding the use of human
subjects in research. It is also recognized in the established practice
of technology assessment, which seeks to find the least problematic and
dangerous means for achieving a desirable end.

For instance, as a means of treating infertility or of providing a
suitable source of compatible organs for transplantation, cloning raises
difficulties having to do with human dignity and the costs of
"manufacture" of the sort discussed earlier. Human cloning also raises
questions about the ethics of research with human subjects, with risks
of harm to the child-to-be, the egg donor, and the woman who would bring
the clone to birth, questions that we shall take up in some detail in
Chapter Five. Yet the most highly controverted moral argument about
human cloning research involves a human subject not always considered
when the ethics of research is discussed: the early human embryo.
Because all cloning begins with the production of embryonic clones, and
because such clones are potentially highly useful in biomedical
research, questions of the ethics of means are absolutely central to the
debate about the morality of cloning.

Ethical questions regarding the use of human embryos in research are, of
course, not unique to cloning. They have been central to the recent and
continuing controversy about federal funding of research on human
embryonic stem cells, because human embryos produced by IVF offer
possibilities for medical advances, beyond their use in assisted
reproduction. The use of embryos has aided research on early human
development. These embryos are also the source of human embryonic stem
cells, pluripotent cells[^7] that may be induced to develop into all the
tissues of the body. These stem cells thus may hold great promise for
future treatment of chronic degenerative diseases and disabilities.

The difficulty arises because the embryos put to use in these ways are
themselves destroyed. This fact raises serious and troubling questions
about the proper way to regard these nascent human organisms and the
morally appropriate way to treat them. Cloning techniques might provide
an even more useful source of embryos for biomedical research than
simple IVF techniques. Human cloning could yield numerous identical
embryos, could provide for the study of stem cells derived from
individuals known to possess genetic diseases, and might eventually
yield transplantable tissues for regenerative medicine that would escape
immune rejection. Human cloning-for-biomedical-research therefore brings
the moral question of means before us with even greater force. It calls
on us to think of the good of medical advances and the relief of human
suffering while at the same time considering our responsibilities to
nascent human life and the possible harms to ourselves and future
generations that may result from coming to regard the beginning stages
of human life as raw material for use and exploitation.

While there is almost universal opposition to
cloning-to-produce-children, the prospect of using cloned embryos in
biomedical research has attracted significant support in the general
public and among many scientists, patient advocacy groups, and
policymakers. It therefore presents more complicated moral and policy
challenges, and requires serious reflection on the duty of society to
those of its members who are suffering, as well as its responsibility
for nascent life. The precise character of both that duty and that
responsibility is a subject of long-standing dispute, giving rise to a
contentious but very important public debate.

#### Cloning and Public Policy

Beneath the current debate about human cloning lie major questions about
the relation between science and technology and the larger society.
Valuing freedom and innovation, our society allows scientists to inquire
as they wish, to explore freely, and to develop techniques and
technologies based on the knowledge they find, and on the whole we all
benefit greatly as a result. We limit what scientists can do only in
certain cases, as when their research requires the use of human
subjects, in which case we erect rules and procedures to protect the
health, safety, and dignity of the weak from possible encroachments by
the strong. In more pervasive ways, we also shape what science does
through public decisions about financial support and scientific
education. With the uses of technology, we are sometimes more intrusive,
establishing regulations to protect public health and safety or to
preserve the environment. In rare cases, we even ban certain practices,
such as the buying and selling of organs for transplantation. Yet, on
the whole, the spirit of laissez-faire governs technological research,
development, and use.

But when innovations arise that appear to challenge basic goods that we
hold dear, or when the desirability of scientific and technological
progress runs up against concerns for the protection of human life and
well-being, we are forced to consider the tacit social contract between
science and technology and the larger society. The current public and
political deliberation about whether and how to restrict or prohibit
human cloning forces us to do so in a most powerful way.

In addition, the current deliberation confronts us with the task of
balancing important and commonly defended freedoms---the freedom of
scientists to inquire, of technologists to invent, of individuals to
reproduce, of entrepreneurs to invest and to profit---with the
well-being of our society and its members. Circumstances in which
otherwise beneficent freedoms can endanger those things that are for us
of the highest importance are most challenging for free societies, and
the prospect of cloning presents us with just such a challenge.

This is not an altogether unfamiliar challenge. There are other
circumstances in which the freedom to explore, inquire, research, and
develop technologies has been constrained. Biomedical science, as we
have said, is restricted in its use of human subjects for research, and
scientists are required to obtain informed consent and take great care
to secure research subjects from harm. Scientific work is also
restricted from activities that might harm the health of the general
public, and from producing products that may endanger consumers. For
example, the federal Food and Drug Administration sits at the juncture
between development and marketing of medical products, regulating their
introduction and use according to criteria of safety and efficacy. Our
society has come to a near-total agreement on the need for such an
agency and the importance of its work.

Human cloning, however, does not easily fall into any of the familiar
classes of our experience with science. Nor do the ethical challenges it
raises fit neatly into the categories of risks to health and safety that
are ordinarily the basis of public oversight of science and technology.
Raising ethical questions about ends as well as means, cloning is at
once a potential human experiment, a possible aid to reproduction, an
altogether new sort of procreative technique, a prospective means of
human design, and a source of embryos and embryonic stem cells for
research. It points back to familiar dilemmas of bioethics---including
the ethics of human experimentation and embryo research---and it points
forward to the sorts of challenges that will face us as biology gains
greater technical prowess. It therefore invites us to think anew about
the relationship between society and biomedical science and to evaluate
the sufficiency of current institutions and practices that govern that
relationship.

The potential dangers we face do not result from ill intent or bad
faith. Neither of the prevailing caricatures in the cloning debate---the
mad scientist on a blind quest for an inhuman immortality or the
puritanical Luddite seeking to keep the future at bay---is accurate,
appropriate, helpful, or fair. The challenge we face is not as easy as
that. The challenge we face involves the conflict of competing sets of
concerns and priorities, each in the service of vital human goods, and
each driven by a desire to improve the human condition and to protect
essential principles. The widely shared desire to cure disease, relieve
suffering, understand human biology, and provide humankind with new and
more powerful means of control can conflict, in this case, with the
widely shared desire to respect life, individual identity, the dignity
of human procreation, and other institutions and principles that keep
our society healthy and strong. The challenge for our society is to
determine, through public deliberation and thoughtful reflection, how
best to adjudicate between these two desires and to determine what form
to give to the tacit agreement between society and science, by which
society promises freedom within bounds, and science affords us
innovation, knowledge, and power while respecting reasonable limits.

The new and distinct challenges that confront us through cloning call
upon us to consider the character of that tacit agreement, and to
determine whether, and in what way, it might need to be amended and
supplemented, especially in the face of the rapidly arriving new
biomedical technologies that touch so directly upon our humanity. It is
our hope in this report to contribute to just such a thoughtful
consideration of the question.

#### The Report

In Chapter Two we present a brief history of human cloning. We summarize
the scientific developments, the various public and political debates,
and the actions of earlier panels and government bodies.

In Chapter Three we discuss the terminology of the cloning debate. We
analyze the controversy over cloning terms, state the terms we intend to
use, and lay out the rationale behind our choice of terms.

In Chapter Four we present a survey of the scientific aspects of human
and animal cloning. We attempt to clarify what cloning is, where the
science stands, and where it may be going.

In Chapter Five we discuss the ethical arguments for and against human
cloning-to-produce-children. We consider reasons to create cloned
children, concerns over safety and consent, and a series of moral
objections.

In Chapter Six we discuss the ethical arguments for and against
cloning-for-biomedical-research. We consider the likely medical
benefits, the potential social and ethical difficulties, and the concern
over the treatment of human embryos.

In Chapter Seven we discuss the public policy alternatives. We consider
various options for government action, and present arguments for and
against each.

In Chapter Eight, we present the Council's conclusions and offer our
recommendations.

[^1]: The term "human cloning" is used in this chapter to refer to all
    human cloning: cloning-to-produce-children and
    cloning-for-biomedical-research. When only one particular use of
    human cloning is intended, we use the more specific term. A full
    discussion of our choice of terminology is provided in Chapter
    Three.

[^2]: *Cloning Human Beings*, Rockville, MD: National Bioethics Advisory
    Commission, 1997. Human embryonic stem cells had not yet been
    isolated at the time of the NBAC report, so the Commission did not
    offer any recommendations on cloning-for-biomedical-research.

[^3]: Chapter Two summarizes selected historical aspects of the
    emergence of cloning research and public reactions to the prospect
    of human cloning. Chapter Four summarizes selected aspects of the
    current state of the relevant science and technology.

[^4]: In order to be sure that we explore fully the human meaning of
    cloning, we shall examine it in comparison with natural unaided
    human reproduction, rather than assisted reproduction, say, with in
    vitro fertilization. The established reproductive technologies do
    provide some useful points of comparison, but they cannot be taken
    as the most helpful baseline for understanding the significance of
    cloning. For that, normal sexual reproduction is the appropriate
    basis of comparison.

[^5]: The term "sexual reproduction" has two related meanings: the first
    refers to the act of sexual intercourse that initiates conception by
    introducing sperm into a woman's generative tract; the second refers
    to the conception itself, the combination of genetic material from
    egg and sperm that results in a new organism with a unique genotype.
    Assisted reproduction techniques like IVF do not involve the former,
    but do involve the latter and are therefore still rightly considered
    sexual reproduction. (Likewise, children who are adopted are the
    fruit of sexual reproduction.) Cloning involves neither, and is
    therefore described as "asexual reproduction." The second and more
    fundamental meaning of "*sexual* reproduction," the union of egg and
    sperm that results in a new genetically unique organism, is the
    basis of our discussion in this section.

[^6]: The apparent exception of identical twins is discussed in Chapter
    Five.

[^7]: Pluripotent cells are those that can give rise to many different
    types of differentiated cells. See Glossary of Terms.