John Sterry from the Ipswich, Suffolk line is our most recent and is the second member of the Ipswich, Suffolk to join. As these two Sterrys were second cousins, an exact match was anticipated.
However, a 2-marker mismatch between them was recorded and both were now 3-markers distant from the calculated mode or 'signature' of the DNA group to which we believed they both belonged. This was rather disconcerting. [Specially selected DNA 'markers' are used to determine relatedness; such markers being passed down largely unchanged from father to son over hundred of years.]
So we sought the advice of two excellent Rootsweb mailing lists: the Guild of One-Name Studies mailing list [available to members only] and Y-DNA-Projects [a public mailing list for the discussion and sharing of information regarding practical issues related to testing for Y-DNA surname projects] as well as the helpdesk at Family Tree DNA.
June Willing from the GOONS mailing list provided a particularly detailed and helpful reply. [The #numbers are the IDs of the two Ipswich line participants in the STERRY DNA Project.]
"I don't see any problem with #349959 being closely related to #169049, even though they have a GD [genetic distance] of 2. #349959 has a mutation on [marker] CDYb which the others in the group do not have. #169049 has a mutation on 385b which the others in the group do not have. So each has picked up one mutation in 3 generations. Nothing unusual in my experience. They both have a mutation on [marker] 570, suggesting they could be more closely related to each other than to the others in the group. Some markers tend to mutate pretty quickly and those concerned in your results, CDY and 385, are among the fast- moving markers.
DNA results do not in themselves prove a relationship, but must be used in conjunction with the documentary evidence. But in this case, in my opinion, the results do not contradict this."
Darren Marin from Family Tree DNA provided an intriguing insight into the possible cause of the unexpected mutations:
"While this is unusual to have two mutations and be related within the past 4 generations it is entirely possible. One way of reading the TiP calculation would be to say we see this exact scenario almost 30% of the time. While what causes mutations is not well understood one thought is that the older a man is when he has a child the more likely a mutation will be to occur since the DNA replication seems to not work as well as when younger. If either of their lines have older fathers this may explain the more recent mutations. "
David Sterry, Co-Coordinator of the Sterry DNA Project comments:
"We were thereby reassured that the two members of the Ipswich Sterry tree were indeed related and that the mismatch could have been the result of genetic mutation in a recent generation, possibly caused by the common ancestor fathering one of his sons "later" in life. In this case we noted that George Arthur Sterry was 24 when Mervyn`s grandfather Ernest Sterry was born whilst he was 42 when John`s father Robert Charles Sterry arrived.
Another feature noted was the sharing of a common marker difference to the combined Lowestoft, Southwold & Ipswich modal indicating an earlier mutation which may be related to the progenitor George Starry being 48 when his son, George, was born.
Ultimately, the suggested connection of the Ipswich line with the Southwold branches and the older Lowestoft tree appears to be firming up.
We would now very much like to recruit a member of the Pakefield, Suffolk line to check out our developing suspicion that the progenitors of both that line and the Ipswich line were brothers! "
