If the whole world media told people that incest was good, would people start screwing their siblings?

Give it time. It's an angle being worked.

Granted, I think we're going to reset things before we get to that point, but no bridge seems too far.

Edit:

I don't believe this theory, no one can convince you to do something you don't want to.

This should be addressed. You're not looking at this correctly. We all want to do terrible things, at least at some level. That's human nature. The issue arises when society (or at least the perception of society) gives you license for your terrible desires.