> Even though I'd prefer not to admit it, biological psychologists
> have provided compelling empirical support for the claim that
> genetics influences various psychological attributes (e.g.,
> IQ performance, sexual orientation, temperament, schizophrenia).
> Granted, this is not based on genetic mapping, but consider:
> (1) the correlation between adopted children and their
> biological parents on many psychological characteristics is
> positive (difficult to explain with nongenetic factors!);
> (2) monozygotic twins (identical twins) are more similar on
> many psychological characteristics than dizygotic (fraternal)
> twins are. Given that each twin pair is the same age growing
> up in the same household, this is again difficult to explain
> without genetics.
It's obvious that genes influence the observable variation in physiological traits like hair color, height, and weight, so wouldn't it be rather surprising if genes didn't influence the observable variation in behavioral traits like intelligence, sexual orientation, and temperament?
-- Luke