Donna Abrego

Hello first time in this conversation and not sure how this works but My ancestors come from Spain and moved to Mexico City and came to California before California was a state. The family linage in Spain cannot be found and am thinking maybe we were Jewish, if this is so how can I find out about Spanish Jews from Spain. My relatives have owned lots of land grants in California and am thinking because that if they were Jews they could not own land in Spain so left own Land in the New World