My girlfriend and I both share the same last name and our families claim they are both from the same Korean surname "clan". This is a huge sticking point for her father. I know so far with certainty that we don't share a great-grandfather just by asking my grandmother about my grandfather's immediate family (my grandfather has passed).
We've been thinking about signing up for 23andMe but I'm not entirely sure how accurate it is. I'd like to know if it would be worth our time doing a gene comparison. We want to know what degree of relation is between us.