We have 0 proof of that, and even if you want to point fingers at homosexuality being the reason that still can also be rooted from celibacy. Now, don't get me wrong i'm not saying this is the only root for sexual deviations, but i'm just saying that it can possibly be one.
Homosexuality (regardless of pop culture) is based/rooted from a persons environment. It is influenced, either through other people or just because of their environment. Priests are normally surrounded by males during their careers and due to the ignored sex drive then whatever is in their area can potentially sexually attract them. It's like in prison. Most of the inmates where probably not homosexuals originally, but the longer they stayed and had 0 contact with the opposite sex they end up getting sexually attracted to whoever is in there.
Here is a fun fact (you probably won't believe), but I do have friends who became a priests.. now, according to him (we were still in college) that before the seminary begins, most of these studying priests are suggested to go to as much strip bars and have as much sex, beer, cigarettes they can because ones they begin the seminary, they will never be able to entertain chemical craves such as sexual desires again. In short, most lose their virginity before they enter their actual careers because it is naturally in us to experience it.