I'd say what you would want isn't really relevant, but I know you're mostly just alluding to biological imperative which is totally fine. At this point my argument is that biological imperative shouldn't even be a factor in whether same-sex couples can marry. It is not what we use to define morality or acceptable behavior. This is why we have prohibitions against -blam!- (sexual assault), and why we don't stigmatize people who choose to remain single or just not reproduce in our laws.