the talk and my step brother

I've been home from college for a few days now and I've been having to share a room with my step brother whose a sophomore in high school... he's noticed that I've been on my period and started asking me questions about a woman's body and sex , we aren't super close but he always ask me for advice about girls... in a way I feel almost uncomfortable talking about it with him but at the same time I know he's very curious and becoming a lot more interested in girls and has a girlfriend but I don't want to tell him not to have sex or anything because I have sex with my bf but I also don't want to encourage it because he is young but I know if he does I want him to be safe doing it ... so from another persons perspective what should I do