What’s inappropriate anymore?

Lynnette • Wife 12-20-17 ❤️ Mom 2-18-20

I follow my sister very closely on her social media activity, she’s 13. I had done some very terrible things on the internet as a child at her age which could be making me more overprotective I guess would be the right word. She openly advertises on twitter that she’s 13 and has posted pictures of herself (her twitter is not private so any creep can see this). Two days ago she posted something about how an emoji looked like 69, I brought it to my moms attention since I have no way of contacting her dad (we have different fathers) and she agreed that it was inappropriate and would tell her dad about it. It’s still up and I’m just concerned not enough is being done. I’m scared of talking to her about it because I don’t want to be a second mom and I don’t want to hassle her too much but I just don’t want her to go down the same rabbit hole I did. What’s the beet course of action? Should I just leave it? I’m not an “I told you so” kind of person so I’d rather not wait around for anything to escalate.