Homosexuality isn't wrong, it fixes overpopulation and that's the reason it occurs in many, many species.

Can't you also use that argument on murder? Like in both non and consensual murder (consensual think of the gladiators)

Incest is wrong, because it limits the genetic variety of potential offspring, leading to genetic diseases

Necrophilia naturally repulses most animals, because it doesn't serve reproduction and might cause diseases.

Neither does having sex with an infertile loved one(not the diseases one) your argument seems to be if it repulses then it's morally wrong

Incest is wrong, because it limits the genetic variety of potential offspring, leading to genetic diseases.

Yeah but what if not in the child bearing intent

Bestiality is rare because as social animals that we are we have to empathize with each other and empathy makes most people repulsed while they witness bestialty.

Again you are using disgust

Empathy. That's mostly just a chemical reaction but, if you look at it scientifically it has no meaning. But your points are well thought out