So, this is I suppose merely an extension of the current crisis the Catholic church as been having as revelations of sexual abuse by the clergy continue to hit the news cycle.

Now it's Catholic nuns who are being accused of abusing young girls entrusted to their care.

https://nypost.com/2019/02/16/inside-the-horrifying-unspoken-world-of-sexually-abusive-nuns/

I suspect that this will expand into more and more accusations as women come out with their own lurid tales of abuse at the hands of these nuns.

My theory as to why this is so prevelent in Nunneries and among the priests is that they attempt to suppress their natural libido by remaining celibate. In the attempt to keep their vows they simply rationalize things I suppose? Combine that with their religious ideology and their sexual urges get perverted. Of course, another factor may be that people who already have issues with sex may be attracted to serving the church.