This supposes that there's some sort of inherent biological, and not cultural, reason for opposition to homosexuality.
I'd be curious to hear evidence of it.
Buddhism has a weird attitude towards it; European observer s in the 16th century commented that Buddhist monks seemed so enlightened and wise... until they began making love to their pupils.
I suppose there's an instinctual fear of what is different or unknown, which can be overcome. If that's biological then I guess I'll agree that people can be biologically opposed to homosexuality. But that makes it sound like people can't overcome the fear, or that it is somehow justified, which is very dangerous ground.
(and no, this isn't 'evidence,' just my opinion.)