Your illustrious medieval ancestors?

I caught a "Who Do You Think You Are" programme featuring Celia Imre the other day. She sought the origins of her son's radical politics and her own feminist feistiness in her ancestors. Here's what the program found for her:

"Imrie’s particular wish to uncover an ancestor to inspire her politically inclined son, Angus, unearthed a corker in her “eight-times grandfather” William, Lord Russell, son of the Earl of Bedford in the time of King Charles II. A leading Whig politician who truly had the courage of his convictions, Russell was such an intransigent defender of Protestantism and lover of constitutional liberty that he was accused of plotting to kill the King, and promptly beheaded.

"At Woburn Abbey, the Russell family seat, Imrie set out on the still more dramatic trail of Frances Howard, grandmother of the aforementioned William. A victim of one appalling dynastic marriage, and caught up in vicious courtly intrigues while trying to secure happiness in a second, she was packed off to the Tower of London with her new husband, accused of murder. Frances was eventually pardoned but history was not so forgiving."

So she had found her 'good genes' then? Not so fast, here's Richard Dawkins:

"For relationships as distant as third cousin, 2 x (1/2)⁸ = 1/128, we are getting down near the baseline probability that a particular gene possessed by [an individual] will be shared by any random individual taken from the population."

Celia Imre's “eight-times grandfather” William, Lord Russell, is nine generations separate from her and shares a relatedness of  1/512 = (2^-9). That distant relatedness could be greater if her lineage includes a degree of inbreeding - but it's unlikely to be more than 1/128 - Dawkins' rough figure for the genetic relationships of any two random ethnic English people.

So Celia Imre's traits for general lefty feistiness are certainly in her genes, but not through the good offices of those specific medieval ancestors.

More generally, you get a dilution down to 1/128 in seven generations. At four generations per century, you may assume that any specific traits of a specific ancestor more than 175 years ago (i.e. before c. 1839) have since been diluted out by Mendelian segregation and recombination. (Also more from 23andMe's reseaches here).

Genetic immortality? fuhgeddaboudit..

"Love thy neighbour" .. why, exactly?

The following observation (Richard Dawkins, The Selfish Gene) has always struck me as both profound and politically illuminating.

"For relationships as distant as third cousin (2 x (1/2)⁸ = 1/128) we are getting down near the baseline probability that a particular gene possessed by A will be shared by any random individual taken from the population."

The 'population' we are talking about here is the co-ethnic population. For example, English people whose grandparents on both sides were also English.

What would you think if you saw someone walking down the street greeting everyone they met with a warm smile and a cheery greeting as if they were meeting their brother or sister? I'd cross over! People at less than 1% relatedness don't stir any innate kin-altruistic feelings in us. And so to the tragedy of the NHS and other 'caring' bureaucracies. Apart from rare super-empathic individuals (aka 'saints') most staff don't have any emotional investment in their clients at all - and why should they? So the default mode is neglect - as on the street. People who create social policies are often smart, highly urbane and empathic individuals who implicitly believe the masses are just like them. Organisations, processes and laws are repeatedly designed as if no-one would ever try to game them for their own convenience. If only!

The other implication concerns your personal contribution to the gene pool. After eight generations your descendants will be no closer genetically to you than a co-ethnic stranger today in the supermarket. So stop worrying about your spurious genetic immortality! But doesn't this contradict evolution? Not really: if the human race was today undergoing strong selection (i.e. lots of people were being killed off by the 'environment' before reproducing) then as a reproducing survivor your genes would disproportionally contribute, and skew, the future gene pool: they would matter. However, in advanced countries humanity today is subject only to weak selection - the gene pool is 'stationary' - so your contribution really doesn't matter at all.

Small caveat: if you're intelligent and civilised and don't reproduce, be aware that the rather dim and less civilised are reproducing just fine: they don't have the distractions of interesting career options. This of course also steers the gene pool so it's not quite stationary.