page_title: Transgenerational epigenetic inheritance
section_title: Blending vs. particulate inheritance
hierarchical_section_title: Transgenerational epigenetic inheritance / Controversies / Blending vs. particulate inheritance
context_page_description: Transgenerational epigenetic inheritance, is the transmission of epigenetic markers from one organism to the next that affects the traits of offspring without alteration of the primary structure of DNA —in other words, epigenetically. The less precise term "epigenetic inheritance" may cover both cell–cell and organism–organism information transfer. Although these two levels of epigenetic inheritance are equivalent in unicellular organisms, they may have distinct mechanisms and evolutionary distinctions in multicellular organisms.
  The environment can induce the epigenetic marks for some epigenetically influenced traits, and some marks are heritable, leading some to view epigenetics as a relaxation of biology's rejection of the inheritance of acquired characteristics.
context_section_description: Addressing these related questions, scientists during the time of the Enlightenment largely argued for the blending hypothesis, in which parental traits were homogenized in the offspring much like buckets of different colored paint being mixed together. Critics of Charles Darwin's On the Origin of Species, pointed out that under this scheme of inheritance, variation would quickly be swamped by the majority phenotype. In the paint bucket analogy, this would be seen by mixing two colors together and then mixing the resulting color with only one of the parent colors 20 times; the rare variant color would quickly fade.
  Unknown to most of the European scientific community, a monk by the name of Gregor Mendel had resolved the question of how traits are conserved between generations through breeding experiments with pea plants. Charles Darwin thus did not know of Mendel's proposed "particulate inheritance" in which traits were not blended but passed to offspring in discrete units that we now call genes. Darwin came to reject the blending hypothesis even though his ideas and Mendel's were not unified until the 1930s, a period referred to as the modern synthesis.
caption: Blending inheritance leads to the averaging out of every characteristic, which as the engineer Fleeming Jenkin pointed out, makes evolution by natural selection impossible.