Jonah: Anyone who has reflected on his own family history, or raised

children, surely knows that a great deal of a person’s temperament is

heritable. Studies of identical twins separated early in life bear this

out.

What is heritable, or part-heritable, though, is broad attitudes:

contrariness, sociability, timidity — things like that. Some such traits

map quite obviously into political attitudes. A prickly, don’t-mess-with-me

individualist is more likely to be libertarian that is a docile, unassertive

go-alonger. Other traits could work either way. A sociable, gregarious

type of person could as easily be Left as Right, surely — in fact a

majority of politicians, of every persuasion, are sociable and gregarious,

or they would find politicking unbearable, wouldn’t they? So while there is

some heritable component to our political attitudes, this is a very fuzzy

mapping.