Well if I cant say the moral is for me, in my view then morality must be objective, in which case the existence of two sexes for it must make it morally right. Remember morality by definition is principles concerning the distinction between right and wrong or good and bad behaviour, so two sexes for it would be the right behaviour and one sex for it would be the wrong behaviour.Just saying "for me that would be morally right" doesn't say why it is a question of morality, which was the question I asked.
Answered aboveUsing biology not for what it's intended in itself isn't a moral question because there's no moral right or wrong involved.
For me no, not least because there is nothing that exists that suggests we should use our lips and breath to play a flute, unlike the biology where the opposite sex exists for sexual intimacyI can use my lips and breath to play a flute which is not what they were intended for, is that morally wrong?
So my question again, what is your reason for one sex acts not being morally wrong?