As far as I knew, my entire family is Indian, and I had always assumed that my parents were the first from either of their families to emigrate. My Y chromosome sequence holds no surprises, then, in indicating that my paternal origin is from the Indian subcontinent. The mitochondrial DNA sequence is more interesting. It says that I belong to a group of people that geneticists call "haplogroup U."

"Taking the mitochondrial DNA from thousands of people [in Europe], they fall into seven discrete clusters," says Brian Sykes, a professor of human genetics at Oxford University. "In other parts of the world there are other clusters -- about 36 altogether -- and they were all started off by one single woman. Those clusters we call clans."

The oldest clan traces back to a woman who was alive 45,000 years ago. And by looking at the present-day distribution and also where the clan showed the most variation (where it is the oldest), Sykes says, you can work out where this woman lived. "In the case of this earliest woman 45,000 years ago, she lived in Greece."

That woman, given the name Ursula, is the mother of haplogroup U and, apparently, my ancestor of 2,000 generations ago. Other "daughters of Eve" include Xenia (25,000 years ago in the Caucasus); Helena (20,000 years ago in the Pyrenean foothills); Velda (17,000 years ago in the Basque region) and Katrine (15,000 years ago in northern Italy).

So does my DNA reveal some hidden family history? Jobling urges caution in interpreting the results. "You've got to remember you have got an awful lot of ancestors," he says. "Every generation, the number of ancestors doubles. By the time you get back to your great-great-great-grandad, there are 32 of them -- that's not very long ago. When you see Y-chromosome or mitochondrial data, you're really only looking at a single ancestor, so investing too much significance in that has to be slightly resisted."

For Jobling, the value of looking at the differences in our genomes is about evolution rather than individual ancestry. One of the spin-offs of the Human Genome Project is the Haplotype Map -- an international project to catalog every single nucleotide polymorphism on the 3 billion-base-pair human DNA sequence. For Jobling, the "HapMap" throws up some new avenues of research: using autosomes as a way of tracking ancestry.

"Instead of the genome being regarded as a pack of cards being reshuffled all the time, some of the cards are stuck together," he says. "They form blocks that don't get reshuffled. You look within those and regard them as just being small mitochondrial genomes or small Y chromosomes sitting in the genome, not changing by recombination but changing by mutation through the generations and providing you with another way to get informative little trees of ancestry within our genome."

The lowest estimate is that 20 percent of our genome is in these blocks. And geneticists are using DNA to uncover relationships in populations all the time. Jobling's colleague, Turi King, profiled the Y chromosomes of 150 men with random surnames and compared them with 150 men who shared surnames. Unexpectedly, she found that sharing a surname means you are highly likely also to share a Y chromosome. Working out how closely related two men with the same surname are is tricky, but the work suggests that there is a lot of information about our social history locked away in our genomes.

"You're carrying the DNA of these ancient mothers and ancient fathers in every cell of your body," says Sykes. "It's a very strong reminder of how one fits into the whole of humanity."

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