Because families over here have tried to hang onto various aspects of their former culture as a form of identity in the "new world."

In a sense you could describe the phenomenon as being a part of American culture. We often describe ourselves as a melting pot where. various cultures and ideas blend into something greater, and part of that process is holding up and cherishing the traditions our ancestors brought here with them.

My mom's side of the family consists of Poles who migrated here several generations ago. We still have a bunch of polish recipes we break out when the family gets together and places we like to go in the Polish part of town even though we don't live there anymore. There's one restaurant in particular which serves a mean duck's blood soup.

It's not like I go around all day pretebding I'm Polish in some kind of weird cultural cosplay, but a lot of families over here cling to their traditions. For the earlier generations it was a way to ease the pain of emigration. For newer generations its a way to be close as a family and feel involved with your past.

I get that the OP here is being a bit silly with it, but I don't get why it upsets people so much.

We're a young nation. We don't have a rich history to draw from. Our people feel sentimental about their origins and family history.