Why are we into beastiality?

[Old Zoo]

I'm new to this whole scene and I've had a long debate internally as to why is this something that me (and we all) into beastiality.

I know that a lot of fetishes are behavioral in nature from experience throughout someone's life but beastiality is something I didn't know existed and as soon as I saw it, it just clicked for me.

So the question is, why is something like this such a turn on for people. Is it genetic, encoded in our DNA?

Anyone's insight would be grateful as it would help me understand myself more.

I always think of evolution when looking for such answers. Each species breaks off from another at some point and as a result it inherits most of the forms and behaviors that its base ancestors had. As mammals we generally got the traits of other mammals, and that would include the sexual attraction. How strongly this attraction got differentiated as we broke away is the key. It seems natural that we will have both similar physiology and behavior of close relatives, and happily this leaves ample room for cross breeding.

The only mystery to me is how few zoos are attracted to monkeys and great apes. Perhaps there is another rule not to mate with our close relatives to prevent back sliding.