My grandparents are from Europe but myself and my Father and six aunts and uncle are all born in the USA. We have always kissed each other as greeting and goodbye, it's just the custom we were raised with. I have a very large extended family, cousins upon cousins so I wonder how my parents explained to me the difference between kissing all those cousins I played with and not kissing the kids from day care to 3 year old me? Like how's a small child to understand that these two dozen kids it's okay to kiss but those two dozen kids no?