A study comparing Y chromosomes and surnames challenges the myth of infidelity

Only one out of 25 descendants are not sons of their registered father, and not one out of ten as has been thought until now, the research shows that those with rare surnames are relatives

The study, published this week in the journal Molecular Biology and Evolution, may allow genealogists to create a more accurate family tree even when records are missing. He also claims that the quoted number of one in ten children born in sin is likely inaccurate.

Dr. Tori King and Prof. Mark Jobling from the University of Leicester studied the Y chromosomes of over 1,600 unrelated men who bear about 40 names, including variations in spelling). Boys inherit the Y chromosome and along the way also the surname from their father. Unlike girls who do not carry the specific chromosome and usually change their last name after marriage.

Inherited surnames were introduced in Britain by the Normans at the time of the conquest. The practice of using surnames permeated from the Norman noble families to all levels of society so that by the 14th century people of many classes bore surnames and by the 16th century it was rare to find a person who did not have a surname.

Dr. King and Prof. Jobling found that men with rare surnames such as Grewcock, Wadsworth, Ketley and Ravenscroft tended to share Y chromosomes that were similar (among men with the same surname), indicating a common ancestor who lived within the last 700 years . However, people with more common names such as Smith were no more likely to have such a similarity than anyone randomly selected from the general population.

"Surnames like Smith came from a person's profession and may have been adopted many times by unrelated people," explains Dr. King. "Less common names such as Swindlehurst were more geographically specific and may have been adopted by one or two people, so we would expect these name bearers to be close."

One of the best known of the surnames studied was Attenborough. A random sample of Attenborrows - including their derivatives such as Attenborrow it was found that nine out of ten men shared the same Y chromosome.

The Attenboroughs are descended from one large family of distant relatives," said Dr. King. "The type of the Y chromosome was the same even in spelling changes, which confirmed that the spelling of names took a formal form only relatively recently."

Dr. King believes the findings will aid genealogists in their efforts to populate their family trees, especially when records are missing and documents are incomplete. A genetic test of two people with the same last name will show whether they share the same common ancestor.

The researchers also looked to see if the relationship between the Y chromosome and the surname could provide information about the historical rate of illegitimate children. People with rare surnames can be very close if the name was initially adopted by one or two people, so anyone who bears that name but has a different Y chromosome than most of the family probably has an ancestor born out of wedlock.

"People tend to estimate at one in 10 the number of children born to married mothers from people who are not their husbands," said Prof. Jobling. "Our research showed that it is likely to be an exaggeration. The real figure is almost certainly smaller than 1:25.”

The study is a follow-up study to previous studies, including two that investigated the relationship between surnames and the Y chromosome. A previous study showed that the Y chromosome can be used for forensic medicine, and deduced from the DNA samples to identify a suspect's surname."

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