Archiver > GENEALOGY-DNA > 2005-06 > 1119652813

From: "Chris" <>
Subject: TMRCA
Date: Fri, 24 Jun 2005 23:40:13 +0100

I’ve just had, I think, a fabulous result. I would be grateful if people would a) check that my interpretation is correct and b) answer a questions I have.

My paper researches indicate a possible 5 family groups sharing surname variants. The two largest being: a family in Durham and in adjacent Yorkshire. Conclusions of previous research have always been that “there is no discernible link”, and that they probably have separate origins.

Subject a) has a well-documented family in Burke’s peerage. He traces his descent directly to a Hugo de Blaykeston alive 1341 at Blakeston Manor, Norton, Durham. Records exist of a Blakeston there a few years earlier. Nearby records exist of a John & Olive Blakeston in the 1260’s leaving money to Brinkburn Priory.

Subject b) can trace his roots to a Thomas Blakeston/Blayston d. 1543 in East Yorkshire. Surname holders in Yorkshire can be found in Yorkshire contemporary to Hugo.

They are a 33/37 match. I’ve searched Ybase & Ysearch and the nearest matches are a 31/37 and 6x29/37 matches.

Based on this I think that one can say conclusively that, contrary to previous beliefs, they share a common male ancestor within the time frame of surnames. FTDNA give the following TMRCA:

100yrs: 4.54%, 200 yrs:30%, 300 yrs: 61.80%, 400 yrs 83.20%, 500 yr: 93.66% & 600yrs: 97.85%

From Subject a) is 20 generations distant from Hugo. And about 6oo+ yrs. That’s about 30 yrs per generation!

Subject b) is approximately 16 generations from Thomas. About 400+yrs or 25 yrs a generation. More in line with FTDNA’s calculations. There must be a way of averaging this into the calculations?

If we take FTDNA’s 600 yrs, they indicate a 97.85% probability of a connection since Hugo. Leaving a small 2.15% probability of the link being pre Hugo.

If I adjust the figures for the knowledge that they couldn’t be connected within 16 generations then we get the following: 400-500 yrs: 60.95%. 600 yrs: 86.45%.*

From which could one conclude that:

A conclusive link exists. The probability is in favour of this being in the 4 generations prior to Thomas (ie 60.95%), but that this may have taken place in the previous 4 generations (ie probability of 25.50%). The odds are that they both descend from Hugo. But that there is an outside chance that this link was earlier.

*The latter loses me, why has that gone down by 11.40%? increasing the 2.15% to 13.55%.

Many thanks, Chris

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