This coming weekend my 5 month old niece is going to be baptized in the Catholic church. Now I am Catholic but my sister is not. Our mother is Catholic but my sister's father wasn't. We have different fathers. My dad is Catholic, though. Now my brother-in-law, the baby's father, he is Catholic too. And although my parents are both Catholic, neither of my grandfathers were. My paternal Grandpa eventually converted to Catholicism but maternal Grandpa never did. But then again, his father was a Catholic...but his great grandfather wasn't.
:) Are you following any of this?
My point is simply to never assume that just because you are baptized in one faith that your ancestors were of the same denomination. The likelihood is that they were NOT all of the same faith. I truly think that in the past a family's particular brand of Christianity depended on the denomination of the church they could walk to. I'm really not kidding.
Just keep in mind while you are researching your family's history that all their baptismal records may not be in the same church...or synagogue.
My grandma's brother-in-law is a priest. Her grand nephew...a rabbi.