I'm not technically white, and I'm Canadian which is only technically "American," but -- close enough. IMO, it's mostly people who are not white americans that define to me what white american culture. Like, if you were to ask me "is this part of your culture?" for various things, I would say "yes" to many things and "no" to many things.

But many of the things that I would say "yes" to, other people might inform me, "no, that's not part of your culture." Jazz, Super Mario bros., rap music, anime, chickpea stew, spaghetti -- I identify these as elements of my culture, or at least my "idioculture" as it were, but people have told me these are not part of my culture.

I think maybe let's stop gatekeeping culture so much and let people live how they like to live. If somebody likes wearing a yukata as a houserobe and they're not japanese, is there really a problem? It's not like they're pretending to be japanese.