In primates, particularly humans, sex has little to do with reproduction. Its all about bonding, but sometimes about aggression and dominance. And sometimes less than, or more than, two is involved.

Old married couples do it, even though the hope of further children is long gone. Even the Pope says that's OK. Young unmarried couples do it because their biological urges are greater than societal controls. When we turned to agriculture and settlement, sex had to be culturally regulated because now inheritance of property was involved. AND THAT IS THE ONLY REASON. And we all know what happens in prisons.

In many societies, homosexuality is even encouraged. Although the term "homosexual" is Latin, the Romans did not have a word for it. And the Ancient Greeks were pretty kinky too. There is only one sex crime, forcing sex on the unwilling, or on children. Everything else is allowed, but that doesn't necessarily mean its mandatory.

Take my word for it. God really does not care who we sleep with. He has other things to worry about.