You discounted epigenetic effects (twice, at least, explained allready) and the matter of consent, as well as human rights and the bio-chemical love mechanism. Let's play along with these exclusions.<quoted text>
Most people are heterosexuals. Does that mean we should ban people?
You've just made my point for me. Morality is subjective. Your actual position is that sex is not sinful. Your conclusion will be that no form of sex is sinful.
My point is that sex is an act of reproduction, first. Any defense of sex that is other than the reproductive act is silly. If you want to protect privacy, I'll buy into that. But that's not what you're doing.
********** POLITICS **********
You don't need sex, insemination will do. So frankly there is no reason whatsoever in the world to have sex at all.
And i'm not even talking about the risk of pregnancies. If it's a boy the mother is 7% more at risk of something going wrong.
Before your 18 your body is not even fully mature, let lone the mental preparedness.(unicef statistics)
Or even the reasons for having a kid: it colours so nicely with the settee. Usually for silly selfish reasons or because the bible says so. Or just because sh!t happens. Or because the government needs workers or more tax-payers, ditto the church. Or because your bloke thinks it's part of status and achievement.
You just impose your idea on us. It's your brain-chid, so start taking care of it. Or abort it.
It's nothing to do with us.