We Inherit from Our Parent's Zygotes

It IS a mistake that biologists used to make, too. They believed that evolution proceeded by accumulating the changes that individuals gathered during their lives. The idea was most clearly formulated by Jean-Baptiste Lamarck, but Charles Darwin sometimes used it, too. The classic example is a blacksmith's son supposedly inheriting his father's acquired muscles at birth. We now know that Lamarckism cannot work because bodies are built from cakelike recipes, not architectural blueprints, and it is simply impossible to feed information back into the recipe by changing the cake.' But the first coherent challenge to Lamarckism was the work of a German follower of Darwin named August Weismann, who began to publish his ideas in the 18 80s.' Weismann noticed something peculiar about most sexual creatures: Their sex cells— ^ggs and sperm—remained segregated from the rest of the body from the moment of their birth. He wrote: "I believe that heredity depends upon the fact that a a small portion of the effective substance of the germ, the germ-plasm, remains unchanged during the development of the ovum into an organism, and that this part of the germ-plasm serves as a foundation from which germ-cells of the new organism are produced. There is, therefore, continuity of the germ-plasm from one generation to another.'

other words, you are descended not from your mother but "from her ovary Nothing that happened to her body or her mind in her life could affect your nature (though it could affect your nurture, of course—an extreme example being that her addiction to drugs or alcohol might leave you damaged in some nongenetic way at birth). You are born free of sin. Weismann was much ridiculed for this in his lifetime and little believed. But the discovery of the gene and of the DNA from which it is made and of the cipher in which DNA's message is written have absolutely confirmed his suspicion. The germ-plasm is kept separate from the body.

The failure of Lamarkism means we do not inherit our genes from our parents, but from their sex cells.