Saturn's right, more information would be needed. i'm guessing your family is pagan or at least know you are. why not invite him to join you on Imbolc, you can do a cleansing in case there is anything lingering.
more likely though he's just going through a phase. talk with him, but don't be pushy or demanding. give him some space, but not too much because he might be growing up, but you don't want him falling in with a bad crowd or something. make a charm or some protection spell then give him some space. again though, more information is needed.