I recently spent a few days with my Dsis, her partner and their two sons ages 5 and 8 and some of the things they did around them shocked me quite a bit. They regularly swore in front of them, I even heard DN1 swearing himself a few times, I told him he shouldn't be saying that but my sister didn't bat an eyelid at it. They also had a horror film on infront of them one night and they talked about playing inappropriate video games for their ages. I wasn't completely unaware of any of this beforehand but I don't see them as regulary as I did a few years ago and having spent a few days with them it's clear it's affecting their behaviour quite a bit. I also know they often smoke weed in the house and a few others things but that's the jist of it. I know people have different ways of parenting but I do find this quite worrying, this could really affect how they are as adults. I also worry about how they might influence my DC in the future, she's too young to understand and copy their behaviour now, I'd like her to see her cousins regulary as they grow up but this may be an issue in the future. I know my sisters loves them, they're looked after fine, clean and tidy and fed but she seems so oblivious of their behaviour, they're never told off or punished. I think it has a lot to do with her partner, she was a different person before she met him. I'm just not sure how to approach this, should I just keep out of it or should I say something? Our DM is quite concerned too but doesn't want to say anything. I did correct my DNs behaviour a few times but she'd just wave it off and say "leave him to it he's fine" or something along those lines. I don't want them to grow up thinking it's fine to shout and swear when they don't get their own way and sitting down my sister and properly speaking to her about it might help but then it also might just start an argument between us