[einhverfr]

See my comments above. We can't directly sense whether someone is male or female. If we could, I am sure the world would be safer for transsexuals.

We have to process what we see, and make sense of what we see in other people before we can find them attractive. Attraction is thus necessarily built on cognition. All you can show with current studies is that there might be a biological reason why aggressively indoctrinating all children into heterosexuality might not in fact cause everybody to conform.