My family do not kiss outside a romantic context, sometimes a parental one. The Prof's family air or cheek kiss everybody, family and close friends. (They have backed away warily from my parents who must have "don't try it" signs on them somewhere I can't see. Pretty funny. They get along fine once the greetings are over.) I think it is cultural. My sibs and I try to adapt to context, but I do hate American style, pull me off balance, hugging, and we, as family, don't. The Sprouts hug their dad, sometimes, without yanking, but not me, though the boys will sometimes plant a kiss on the top of my head.