Is my "stepbrother" gay?

Okay try to follow... He's my Stepdad's daughter's husband's son (not hers) and therefore no relation to me... He always says he likes girls and such, but he likes to wear "skinny" jeans and loves spending the night with me. He is 16 and I don't know how kids act now... (I'm 24). He likes staying with me even though he knows I'm gay and likes me to take him places and buy him things....