On the other hand I can see why people who grow up as just "white," especially "white American," are interested in exactly what particular kind of white they are. Most but not all POC and immigrants know where they came from and what their ancestral home countries are and can point to a place (a notable exception being black Americans descended from slaves), but many "white Americans" with no recent immigrants in their family tree don't have or know that for sure. I've seen lots of African-Americans with slave ancestry also very interested in knowing exactly where their ancestors came from.
I'd probably be curious too, if I didn't already know.
Re: genealogy
On the other hand I can see why people who grow up as just "white," especially "white American," are interested in exactly what particular kind of white they are. Most but not all POC and immigrants know where they came from and what their ancestral home countries are and can point to a place (a notable exception being black Americans descended from slaves), but many "white Americans" with no recent immigrants in their family tree don't have or know that for sure. I've seen lots of African-Americans with slave ancestry also very interested in knowing exactly where their ancestors came from.
I'd probably be curious too, if I didn't already know.