We are lifetime atheists with completely different backgrounds, me a baptiized catholic (as a baby) and my wife sefardic Jewish, her family migrated from Portugal to Amsterdam in 1497 and they have a very interesting and well recorded family history.
My huge family comes mostly from the Aachen region in Germany, Belgium and the South Netherlands. Mine workers.
My grandma had 14 kids, you know catholic and all.
We never felt uncomfortable with each other but our families didn't get along well, they are not on speaking terms.