Cousin panty sniffing

well for some reason i have this strange obsession with sniffing my cousins thongs and stuff like i know that its wrong and i usually feel bad afterwords but she always gives me like ideas like she will always say say like "lets keep it in the family" or something like that lol but i know she just joking and even my sister noticed and called her out on it to but this usually happens when we get drunk but i dont have any intentions of doing stuff with her like that but she does little stuff like that and she like shake her as in front of me or like flash or something also ive never had sex before and idk just the thought of smelling her underwear or doing it just gets me excited is this normal?