[Probably NSFW] Why do some people have sex with animals?

Okay well I was just wondering because it’s so bizaare and disgusting (for me). I have read some articles about it and saw this question.

I’ve also seen a few videos before. The first video I saw before was a guy who was caught having sex with his neighbour’s (I think) chicken, the second one was a video that circulated on Facebook of a guy who’s having sex with his pet snake. Jesus it’s so disgusting I feel the disgust all over my body it’s giving me chills. Poor snake. The video was deleted in a couple of hours.

Oh, and one time I saw a porn of a woman having sex with a horse. I was watching porn and I have no idea how I got to that video. I guess I was kind of curious when I saw the thumbnail and clicked it, and I’m pretty sure that it scarred me for real.

Is bestiality legal in where you live? What can you say about it and why do you think some people do it?