Men who share the same surname have a 25% chance of being related, a British study reveals. The rarer the surname, the greater the chance of random pairs of surnames being related (The Scotsman, 22 February 2006). So there is little hope of building a large family tree for the Smiths, Joneses and Taylors, but there are much improved chances for the Attenboroughs and Grewcocks, for example.

For the study, which was published in Current Biology on 21 February 2006, researchers recruited 150 pairs of English men that shared the same surname but were not knowingly related. About a quarter of these men were genetically connected through their Y chromosome, meaning that they must have shared an ancestor more recently than 20 generations ago, or about AD 1300, when surnames were first used in the United Kingdom (New Scientist, 22 February 2006).

Y chromosomes are inherited from father to son, and surnames are inherited from father to children, so men who share surnames are also related. Has this work merely told us what we know already? Yes and no. Complicating factors such as illegitimacy, adoption and multiple originators would increase the chances that two people with the same surname would not be related (Seed Magazine, 27 February 2006).

That striking strong signal immediately suggests a practical application. Forensic scientists could use DNA retrieved from a crime scene to predict the surname of the suspect (BBC News, 21 February 2006) when used in combination with other intelligence. Indeed, Brian Sykes, from the University of Oxford, recommends that we create a Y-chromosome database (The Scotsman).

The bottom line is, if you think you've got criminal tendencies, you could do worse than change your name to Smith.