Which is about half a decade after the usual end of puberty (according to http://en.wikipedia.org/wiki/Puberty#Differences_between_male_and_female_puberty at least) and “happens” to coincide with the age at which I became serious about exercising daily and not eating too much. (Plus, nothing similar happened to any of my recent ancestors AFAIK.)
Genetics can affect any stage of life, and the steady pressure of existing genetics can have effects at a different time. If your informal argument was right, heritability of traits would never increase after puberty; for some things like intelligence, it does increase steadily over a lifetime.
Or maybe a certain part of your genetics kicks in at a certain age.
Which is about half a decade after the usual end of puberty (according to http://en.wikipedia.org/wiki/Puberty#Differences_between_male_and_female_puberty at least) and “happens” to coincide with the age at which I became serious about exercising daily and not eating too much. (Plus, nothing similar happened to any of my recent ancestors AFAIK.)
Genetics can affect any stage of life, and the steady pressure of existing genetics can have effects at a different time. If your informal argument was right, heritability of traits would never increase after puberty; for some things like intelligence, it does increase steadily over a lifetime.