Saturday, 19 October 2010 INDEX

Fighting crime with Y line

Y line DNA is not like most of the rest of your DNA. At conception most of your DNA gets mixed. Some of the DNA is extracted from your mother, some from your father. But Y Line isn't like that. It consists of the additional chromosome that belongs to the male alone. Women are usually XX. Men are usually XY. Since women don't have Y, male babies inherit the Y line unchanged from their father.

As a result, Y line DNA is identical to the father's Y line and his father's Y line. In theory this should go back to the beginning of the human species but in practice there are small modifications to the Y line, though these occur very infrequently.

The upshot of this is that if you find Y line DNA you have a good chance of knowing the surname of the person you are seeking (if that person has the same surname as his father). The individual may never have given a DNA sample, yet the fact that male relatives have given samples (or the family group can be found on one of the many genealogical sites specialising in this type of investigation) is sufficient.

All this makes more or less redundant all the human rights cases dedicated to preventing the police from having access to the DNA of people who they have come into contact with, but who have not subsequently been convicted of any crime.

And the police would be very foolish not to use this system. Suppose a serial killer is at work and the police had 10,000 names of contacts in a database. If it turned out following one of the murders that the police could have known the surname of the murderer (and perhaps cut down that 10,000 to less than half a dozen) the relatives of the victim may well sue the police for incompetence.

The 1998 Human Rights Act enshrined the right to life (from Article 2 of the European Convention on Human Rights) into British law. Is it possible that any police force failing to take into account Y line DNA would be risking contravening this act?
Saturday, 19 October 2010INDEX