Re: Ch. 3 - Genes, development and instinct
That's true. But take sexual orientation -- I'm not that familiar with the empirical evidence on heritability, I did a quick Google search. I believe that in twin studies it shows that you don't have a 100% correlation. But to me, I still think of it as a genetic predisposition and I think of it as having a "genetic cause" even though the environment might affect whether those genes are expressed. I don't know if the author would say that's the wrong way to think about it.