I'm very into genealogy, and in let's say the Occidental areas (Europe, West Asia and Asia Minor) the intermarriage of rulers and their desirability for further intermarriage pretty much has everyone related to everyone. If you look at one village or family line, there is enough diversity that I'm not sure a population analysis is going to give you the right answer- there is and was still a considerable amount of variation in a population.
I actually had genetic testing done through 23andme.com as well as additional genetic testing related to specific conditions. Obviously I can't comment about the results on a public message board too specifically, but there was one thing I would call a surprise that I now have additional ongoing screening for, the other things I already knew about or was being screened for because of family history.
ETA: Instead of a population view, specific family history can be useful.