Sister

Sure you should because that is your sister but then again she is just going to do what she wants.. Just try to tell her how you feel about it.

leave it alone, just tell her not be stupid and do things she will regret and to b smart about things..if you see that its not bothering her, him touching her then theres not much to worry about. theres not much you can do but just give her good advice

You did not say how old your sister is…I presume she is a teen…if she is not 18 then tell this boy to keep his hands to himself or you will make sure he does…If your parents care…tell them about your suspicions…you just mamy save her from making the biggest mistake of her life…

You need to stay out of it , if you are worried about her not being safe with sex and stuff let her know about the risks and all of that . Let her be a teen and if she wantes to be touchy with him then let her. Its not you right and if you dont like watching just leave the room till they are done or ask them not to do that infront of you. Yours truly, Demika Ray