Hi Bruce (not the singer/songwriter!) (we often received phone calls intended for Bruce/singer/songwriter's father when I was a child),
I am also descended from the Cockburns of Duns, but - alas - I am a female, so not a candidate for your genetic study.
I just wanted to point out that you have a CHRISTIAN COCKBURN on your list of Cockburns. I feel quite certain that this Christian was - in fact - a female, as this was a very common feminine name in Scotland at that time. (Likewise "Murray", believe it or not!)
I feel quite certain that my Cockburn lines intersects yours, and would love to confab on data if you've the time or inclination. 'Sorry that I cannot help with the genetic study.
Tracy (nee Cockburn) Trim