I think Button just wanted to say 'Genetic make-up' and thus sound smart =]
I don't think desire aimed at a woman's chest is genetic, nor the junk about how we don't want it because of jealousy. Why is it that only humans feel this form of genetic attraction to a particular body part? I don't see my cat staring at another's ear.
As Sixty said, if it were genetic then the feeling would be universal. And there would have been some issues back in the day when everyone walked around naked.
I disagree with you, Sixty, when you say fetishes are 'learned behavior.' Is me liking to cook learned? Well, that probably is, as my parents cook a lot, but you see what I'm saying. A lot of tastes or preferences have had virtually no influence during your life, but you still feel that way. I don't think that's genetic though, it's going into areas that we don't really understand - The human mind, and what makes it tick.