Unlike the case of mice and men, this is not a genetic difference, for your cells have essentially identical DNA. The difference is ‘epigenetic’—outside of the genome. This has been known since before the discovery of DNA—the word was coined by Conrad Waddington in 1942—but it has become disappointingly popular to trumpet this as something unexpected, even as a threat to our conventional understanding of genetics. Newspapers state with ill-informed astonishment that ‘new’ research shows the environment can modify which genes are turned on and off. Well of course it can! Embryology depends on
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