A teenager born to a donor sperm traces his genetic father using the DNA test and some Internet searches, raising ethical and social concerns about assisted reproduction that were not thought of when it started.

A 15-year-old boy who was born to an unknown father using a donor sperm has succeeded in tracking down his father, using just the DNA test, genealogical records and some ingenious Internet searches.

The boy tracked down his father from his Y chromosome, which is passed from father to son unchanged. The gene variant patterns it carries can help trace the concerned paternal line, according to a report in New Scientist. All that it cost the boy to trace his father was $289 paid to FamilyTreeDNA.com for the service. In fact, his genetic father had never supplied his DNA to the site. For investigation, the site needed someone in the same paternal line to be on file. After nine months of waiting and making his contact details available to other clients, the boy was contacted by two men with Y chromosomes closely matching his own. These two were strangers, but the similarity between their Y chromosomes suggested there was a 50 per cent chance that all three had the same father, grandfather or great-grandfather.

Though the boy’s genetic father was anonymous, his mother knew the donor’s date and place of birth and his college degree. Using another online service, Omnitrace.com, he bought the names of all who had been born in the same place on the same day. Only one man had the surname he was looking for, and within 10 days he had made contact.

This ingenious investigation using the latest in Internet technology has massive implications for thousands of people who were conceived using donor sperm. There is an explosion of information of genetic inheritance, which will make unknown fathers visible. Anyone who has donated his sperm can potentially be traced by his biological offspring. As more genetic information becomes available online, finding a donor father can only get easier.

FamilyTreeDNA.com, with a database of over 45,000 Y chromosome signatures, is running 2400 projects to trace particular surnames.

About 25,000 people have been born from donated sperm in the UK in the past 15 years. Also, around 90,000 donor inseminations happen in the US every year. The news will be especially unsettling for men who donated anonymously before the power of genetics was fully appreciated. Donors were often college students who traded their sperm for a little money. Many of them, now married and with kids, are likely to face the implications of having a dozen offspring suddenly wanting to meet them.

And the implications could have tremendous forensic ramifications too. Police could perform similar searches to identify a criminal's surname, giving vital leads in a case.