This. 100% correct. Harry Potter is more believable than what gets posted on incest threads. I am obsessed with dad-son incest, but seriously - reading stories here and in reddit makes me laugh. Incest is such a big taboo (esp parent-offspring incest) that it very very rarely occurs. And when it does occur, it usually is the product of abuse etc. But for consensual incest, if it were to occur, there would be so much guilt, hesitation, apprehension, fear, sadness, devastation etc that it would not occur in the way people write them. I am not saying it does not occur at all -- with over 7+ billion people, pretty sure it does occur in many places, but I can say for sure that the amount of ifs and buts and yes and no's that people go through before it were to occur that it would not happen in the way it is described. People would be way too devastated to even speak about it, let alone write it like that so openly.
I mean most incest stories go like "I found my muscular and ripped dad masturbating his 10 inch cock. I felt so horny seeing it that I immediately went to him and started kissing him. He responded back. Then he tore my clothes and started barebacking me with his monster cock. We had the best sex of our lives..."
I mean, all the dads happen to have 8+ inch cocks, all of them are muscular and ripped, and sex happens like breathing happens - it's so easy and quick like you get that everyday... I mean at least make it believable. Show the shame, the guilt, the hesitation, the fear, etc... even sex between non-relatives aren't that easy in real life (unless you are in a bathhouse oe smthing...).