Resources for looking into possible Jewish heritage?

For years there have been rumors in my family (on both sides) that we’re Jewish, but I’m finding it pretty impossible to verify.

My dad’s side is Colombian and our family seems to trace back to Murcia Spain. A few members of our family are very vocal about our Jewish heritage, but they don’t have much to go off.

Outside of a few Christian aunts nobody on that side of the family seems to practice any religion in particular. My grandfather collected books on world religion, but wasn’t religious himself. My grandmother was agnostic.

On my mom’s side it seems like more of a rumor. My grandmother was very catholic, but my great grandmother didn’t seem to be very interested in religion at all.

Notably, she chose to have my grandmother in a Jewish hospital further away from home after immigrating from Eastern Europe. Not that that means anything neccesarily.

I can’t find any records past my grandfather on my dad’s side and it’s murky on my mom’s side. Any help would be appreciated