Ultimately, zoophilia, as in they preferentially bond and have sex with animals, rather than it just being any kind of "stray tail" they can land, be it human, animal, silicone fleshed out robots, whatever, are actual MORE rare and serial killers. There are something like 30 to 1 MORE serial and spree killers than zoophiles by population.

So ultimately, the psychology of zoophilia is studying a hyper minority. From what little they found from the oh, 500-2000 ish in the english speaking world, there seems to be a more generalized bond with mammals in the mid-brain, more openness to attractive pheromone triggers, and not as much with their own species.

Now the mentally ill, who just tend to fuck random things, called it generalized paraphilia. Or people into risky/exotic sex, those are way way more plentiful. This is usually neurotransmitter dis-regulation. .5mg of risperdal a day, and magically it stops being an impulse, because the brain is no longer trying to fry itself. The thrill seekers, that's a bit more complicated. They're probably going to kill themselves from auto-erotic asphyxiation in the end, so, who cares? :D

You get into rural areas which are sexually repressed, like during the Kinsey study on male sexuality in the 40s-50s, and its all fucking bets are off. Similar with the Arab world, and many other regions. Its a transitional phase, so people can get their rocks off without knocking up someone in their teens and being a social pariah. When they get older, and more financially stable, most end up boringly vanilla heterosexuals.

As for studies of actual zoophiles, the Indiana study was kind of a wet firecracker. They got a bunch of code geeks/aerospace guys with IQs over 130, who had xNTx type Meyers-Briggs personalities, etc etc.. You lock them up, kiss the fucking internet goodbye. :D Most of the new laws on zoophilia were aimed at the more reckless people making porn of it, and fence jumping. In the rural states, the laws protecting factory farmers who torture chickens, turkeys, assorted livestock, generally keeps the wealthier zoophiles who own their own farms, etc from being blackmailed by their mexican or otherwise ranch hands. Violate ag gag, rack up a felony, back to Mexico boyo! ;D

People just into the porn of animal sex, or human-animal sex.. Mostly novelty seeking personalities. If that porn goes away, they hit the internet and find a new fetish in about 5 minutes.

So most of this zoophilia panic is just bullshit. Granted, that doesn't keep certain senile as FUCK former sheriffs in Arizona from blowing $3-4 MILLION a year trying to lure them to Arizona and bust them. For reasons. :D Or any other wacky assed shit for someone trying to make hay persecuting a super minority and making a name for themselves. Which might get them a step up in their career, but is ultimately limiting because you don't want someone into spectacles and ridiculous bullshit at the higher levels of the justice system on investigative issues.