>>718287086
Someone has already mentioned one reason, though he added "was" unnecessarily. Fun fact, homosexual couples are eighteen times more likely to adopt boys!
In addition to being explicitly forbidden by Christians, Pagans, and Muslims, there are a number of secular reasons why a state may wish to ban sodomy. For one, even with the invention of the condom anal sex is a hotbed of terrible, terrible diseases. Interacting with human fecal matter is a universal taboo for a number of reasons, and it has been widely understood that poop was a source of illness prior to recorded history.
Also, most of the human population that is not afflicted by certain brain parasites, or a pornography addiction has a intense disgust response to seeing homosexual relationships, and this is even observed in children, so evolutionarily humans developed this aversion to homosexuality.
Any one of these would be enough for laws to be passed discouraging the behavior, but sadly this isn't even every reason to prohibit homosexual behavior.
