Answered on Quora.
The PC line is that homosexuality is widespread in the animal kingdom. Actually it’s not. This line is taken to extremes recently, and it is not uncommon to hear PC types say that 10% of all types of birds and mammals are gay. That’s clearly nonsense.
There are cases of two same sex birds incubating an egg, but apparently there was a shortage of the opposite sex that gave rise to this.
I had a cat once that went into heat. You can hear and even observe when a cat is in heat. I won’t go into details. You will have to figure it out for yourself. When this cat was in heat, one of my female cats tried to mount the female in heat!
Bonobo chimpanzees (at least the females) are apparently often bisexual, but I am not aware of any gay bonobos.
If you drive mice crazy enough in the lab or subject them to very crowded conditions, male mice will attempt to mount each other. This is called lordosis. This pseudo-homosexuality is a side effect of the mice being driven crazy by overcrowding or whatever.
However, sheep are a good case for homosexuality in the animal kingdom. Approximately 6% of male sheep prefer to mount other male sheep. I am not sure what they accomplish when they do that, but that’s what they do. They don’t have sex with female sheep. That is quite an excellent analogy in the animal world to male homosexuality among humans. As far as why sheep are like this, I have no idea at all.