My bro and I share the same enthusiasm to eat lots of raw wasabi when eating Japanese food, but we didn't mimic that from each other. It was actually some time after that we realised we do this. It's the same way we like to chew on the ends of straws or such when we have drinks. Today bro nibbled on the end of his plastic stirrer unconsciously while he had coffee, and I got fascinated watching him. Can these traits really be genetic? We're not twins and my mum doesn't have these habits. So where did we learn to behave the way we do?