[All-In Flynn]

{Edit: It's so late it's early where I am, so I won't bother revising what follows - just bear in mind that I hadn't seen your post at the bottom of page 3 when I wrote this]

I seem to recall studies by Helen Fischer (sp?) indicating that it may be women who determine with whom they will mate - selecting the most desirable male. This could plausibly render lesbianism a genetic non-starter - as to the males, it again seems plausible that a gay male would be less likely to compete with the same vigour as a straight counterpart.

Yes the conditions are not binary, and I personally subscribe to a 'spectrum' theory of sexuality, but I find it difficult to reconcile this with a genetic basis for gayness.