There goes Robert E. Lee (you too may be related)

I had heard people on my mother’s side of the family say that we were somehow related to Robert E. Lee.  I was finally able to figure out through that, indeed, there is an actual connection to General Lee.  It was, however, from my father’s lineage and not my mothers, which does make me wonder.

I am not sure if claims of distant lineage connections really amount to much, since you inherit half of your DNA from your father (mother), 1/4th from your grandfather (grandmother), or more generally, 1/(4(n+1)) from your great*n-grandfather (great*n grandmother).

  • great-grandfather 1/8
  • great-great-grandfather 1/16
  • great-great-great grandfather 1/32
  • etc.

So, there is a very diminished influence from any single individual over the centuries (not that many centuries even).  In other words, my common ancestor with Robert E. Lee is 17 generations back, giving me 1 part in 131,072 from the standpoint of genetic influence.

I have also had to explain to some of my relatives who were excited by this little discovery (I suspect that if you have a lot of time to waste, you could probably find many such connections to other past and present celebrities) that we are not direct descendants of Robert E. Lee.  You have to go back five generations, so that we have a further 31/32 = 96.9% dilution of DNA to get back from Robert E. Lee to Richard Lee, who was our common ancestor.  Therefore, I personally have 1 part in about 4 million in common with Robert E. Lee.  Much less exciting.

Really 1 in 4 million is a worst-case figure.  To be more accurate, I would have to trace back every single ancestral path and compute the tiny fractions corresponding to Lee-Lyke intersections and add them all up.  I’m guessing that this might bring me up to 1 part in 2 million or so, if I’m lucky.

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