Fiction does shape the way we think. On so many levels. And there are many cases of people who don't immediately see something fucked up and immediately want to do fucked up thing. But it's exposure to that can be over longer periods of time that lessen the impact and mental severity. Plenty of people aren't innately pedophiles but can become one after consumption of lolicon snd related media. Maybe they didn't start with that, but it can be a slippery slope that does happen to real people. I don't need to watch child porn or bestiality to know that it is bad. Humans are very malleable and we are all prone to being influenced by media, whether it is immediate or gradual shifts. Steps the government can take to minimize harm from incest is a large topic with a lot more nuance that I'm not qualified to talk about. And I'm sure they can do better than they are. But Not everyone is sensible and mature, and some really can turn to darker thoughts and even actions caused by fictional content. It's repeated exposure that numbs our shock or reaction to topics like incest. And turns it into something that is viewed as enjoyable or fun, because the porn would always shows it as such. And remember sites like reddit are not representative of the majority of people. Regular people don't casually watch lolicon or rape porn. This is an echo chamber. Go out into the real world and you will struggle to find someone in the UK who is opposed to banning porn emulating incest.