I never said you were a Nazi. The Nazi party hasn't been active since 1945, in small part because of my grandfather's military service fighting fascism in Europe. I trust you respect his service and that of millions of other soldiers and civilians by also being against fascism.
Are you willing to define your culture?
Does your culture include Catholics? JFK famously was accused of being a papist, and Prohibition was in no small part due to xenophobia about Catholic immigrants to the US, who didn't share "our" culture.
What about Catholics who send their kids to Catholic school instead of public school? Mormons who do the same? Does it include Amish who speak their own German dialect, with their own religion, parochial schools, and culture?
What about atheists? Homosexuals? Trans people?
Does it include the children of Cuban refugees who grew up in the Little Havana part of Miami, with Spanish as their first language? Who celebrate Nochebuena and quinceañeras instead of Christmas Day and Sweet 16s?
Does it include native Spanish speaking New Mexicans whose family has lived in the state since Imperial Spain colonized Nuevo Mexico in the 1600s?
Does it include Native Americans? Would you shy away from medical care from a Native American physician? Would you prefer to not work with a Native Hawaiian?
Is your definition of "culture" simply "born in the US"? Does it include people from American Samoa? Puerto Rico? Guam?
Does it include people with US citizenship who have never lived in the US?
Does it include someone from Canada? Does it include someone from a Canadian First Nation?
I think you see how simply saying "your culture" doesn't really make sense given that the US - and I think nearly all countries - contain a multitude of cultures.