Incest is common. We even can be found in porn.

My(22f) and sister (19f) just discovered we went to the same college as well as the same High School as one of the most popular pornstars on pornhub. I saw her on the front page last night, as I don't watch porn often but was having a hard time sleeping. So next morning I called my sister and said I found out a porn star that goes to our college. She said hey what ones that?! She was the porn star I was telling her about. Our college has a total enrollment of 3,500. We have never met her even though we've all been at the college at the same time for 2 years. So who knows maybe our first time will be an incest scene with her! But I'm married with 2 kids and don't think my husband would allow it but I definitely told my sister to go for it.