For example, scientists at the University of Massachusetts are testing sperm and examining its genetic makeup before it's mixed with eggs. Procedures like PGD also can tell parents which embryos will produce boys and which will grow into girls. But some scientists worry that the procedures will one day become commonplace. They also worry that screening out disease like breast cancer may screen out embryos that might have grown into highly productive people. Long-term implications for gene pool Dr. French Anderson of the University of Southern California, who some consider the father of gene therapy, wants fetal gene therapy only to be used to cure disease.
Scientists also worry about the impact of manipulating genes on the gene pool.
Anytime a new gene is used to alter an embryo, it has the potential to change the genetics of generations to come. Pages will open in a new browser window External sites are not endorsed by CNN Interactive. All Rights Reserved. Terms under which this service is provided to you. Read our privacy guidelines .