My 14 year old cousin collects blood, hair and skin flakes from people, do you think he will grow out of this?

He makes dolls up to look like the person he took the bodily stuff from, then he hollows out the dolls and keeps it in there. Sometimes he asks for these things from people but mostly he gets it without their permission. He gets in trouble at school because when he sits behind someone he will poke the back of their neck with a needle to get blood and pull little pieces of their hair out. He really likes when people have dandruff and sit in front of him so he can collect their dandruff flakes.