Why is heterosexuality the norm?

[Brutalyst]

Soleron said:

Brutalyst said:
you would struggle to find many who arent hetrosexual and only procreate for the purpose of creation. 

This isn't true. In addition to the whole categories of animals that exhibit hermaphroditism (simultaneously, or changing between sexes sequentially), there are plenty of animals that engage in sexual behaviour for social or entertainment reasons including self-stimulation, homosexuality, and mating behaviour out of season where pregnancy is not possible.

I'll take your word for it as I was merely making an assumption :)