DNA testing for ancestry

MtDNA generationsA growing number of people want to trace their ancestry through DNA and understand what the results mean. For those ready to take the plunge into the world of DNA testing, some advice may be helpful. Firstly beware of firms over-selling their products with misleading marketing. University College London debunks some of the worst practices.


Some firms aim to test only DNA markers of interest for genetic genealogy. The favourites are the uniparental lines: mitochondrial (mtDNA), which is passed down from mother to child, and Y Chromosome DNA (Y-DNA), passed down from father to son. Geneticists have identified haplogroups (groups of markers) in both these types of DNA, and drawn up the relationship between these haplogroups in phylogenetic trees. The trees are maintained online at Phylotree.org (mtDNA) and Phylotree.org/Y/ (Y-DNA). Y-DNA haplogroups are particularly fascinating to genetic genealogists since they can be linked to surnames.


However these two lineages are only two of the multitude of your ancestral lineages. It might chance that your Y-DNA comes from an unexpected wanderer, unrepresentative of the majority of your ancestors. So those tests which include enough genome-wide DNA to compare you overall to world-wide population samples will give a more rounded picture. Be aware that some are far better than others. For a detailed comparison of products and prices, see the guide by Tim Janzen for the International Society of Genetic Genealogy.


Most testing firms attempt to interpret your data for you. The problem is that this is a young and fast-moving science. It is hard for firms to keep pace with sometimes radical changes in thinking about the origins of various genetic markers. Discoveries in recent years from ancient DNA have overturned many assumptions based solely on the DNA in living people. That's where Ancestral Journeys could come in useful, but the first edition was rapidly outdated by the deluge of new data. Even the second edition (2015) will be outdated in time! So if you have queries, you might like to pose them on the internet forum Anthrogenica.


Much recent knowledge of Y-Chromosome markers has been pushed by citizen scientists. Two firms are offshoots of the process. Full Genomes can provide the full sequence of a Y-Chromosome, while YSEQ will test a sample for specific markers. Neither is recommended for the novice.