Originally Posted by mlove

I'm referring to porn, but I can see non-adult tolerance of a subject furthering what is common in the adult industry.

As far as your second point, the commonality it depends on the culture of the market you are referring to. Your profile says that you are in Japan, and I believe the japanese industry has been pushing the direction of acceptable perversion that the rest of the porn industry follows.

I've mainly noticed it becoming more popular in my daily duties as a sysadmin for a large adult hosting provider. This past year and a half, we have been seeing more and more incest-related domains popping up, with these markets targeting western users.