After getting some ancestry results back from a personal genome service, I showed as having an Ashkenazi percentage indicative of having at least one Ashkenazi GGG grandparent. Now if that grandparent was a woman.... That would make me halachically Jewish yes? Also, my haplogroup has great prevalence among the Sephardim. So odds are in my favor I'm already Jewish. My family on my mothers side is from Hungary/Ukraine/Russia, and my father's side is Spanish.
My greatgrandparents on both sides were born in the US, and in the time of my elder generations it wasn't always a "great time" to be a Jew, especially in the geographic areas, so my immediate family does not have any knowledge of past Jewish links.
I am converting just to be positive; but isn't it fascinating how things work?? Does anyone else have a similar situation?
You would need to be descended through only female ancestors up to that great-great-great-grandmother since any sons cannot by themselves pass on a halachic Jewish identity, and some Jews would say that the Jewish line ends if any of those ancestors converted to another religion before having their daughters, so the odds are may be somewhat low for you to be halachically Jewish. However, you could easily have Jewish ancestors on either or even both sides of your family, particularly the Spanish side since there were lots of forced Jewish conversions during the Inquisition.
I do believe that many descendants of Jews do carry some special connection to Judaism that draws them to it. That could certainly be one reason why you are attracted to Judaism.