I don't have an answer, but I did a quick google search, and it seems like the descendents of John Pigg Martin are really on top of DNA testing. It's particularly interesting to see it in action to prove centuries-old lines! (The ancestry.com DNA testing tagline that brick walls are no match for cotton swabs must be pretty irritating in JPM's case, since it disproved the "legendary paternity" of the General, which would presumably leave an easy paper trail.)