DNA has been described as our biological blueprint. Biology is not the same as culture. Often there can be overlaps between the two, but I am cautious about claims by some genetic testing companies that they can tell you about how your distant ancestors self-identified. Actually what they are giving you is a correlation between your DNA and what other people have reported about theirs. Some of them are probably mistaken.
My own case is a good example. My Y-DNA is from a common West European haplogroup, but my lineage (the paper trail) is Sephardic. Possible as genetic testing become more popular, sophisticated and detailed, we shall better be able to better correlate known identities with DNA.
GEDMatch, a site where you can find autosomal (see below) DNA matches with others, provides seven ‘Admixture Utilities’ which seek to turn your biological data into something more tangible. I think all the commercial testing companies do something similar – it is good marketing. I am sure the genetic testing is good science, but that data is then matched against self-reported ‘ethnic’ information which might range from carefully studied to utterly fanciful. Various tests told me I had West African, East African, Oceanian, South East Asian and Siberian ancestry. Any of these might be possible in some forgotten past, but each of these ethnicities might equally tell of a European who had gone to live in those places or someone who has provided inaccurate information.
There are three main DNA tests being sold by commercial companies:
Y-DNA in men is inherited from your father’s father’s father… I think this is fun because geneticists now offer maps of different haplogroups’ routes from east Africa to where-ever they ended up. Geneticists make TERRIBLE historians but I see no harm in showing a route out of Africa in the introduction to your family history (and you MUST write down what you know, to share with relatives).
Mitochondrial DNA (mDNA or mtDNA) is shared by women and men and comes from your mother’s mother’s mother… A child of a Jewish mother is Jewish, but I know of nobody who would accept DNA evidence. A detailed mtDNA test might help you find people with common ancestry going back around 1,300 years. This can be quite useful for researching matrilineal Ashkenazi Jewish ancestry, but not for Sephardic. Ashkenazim start with a much smaller gene pool.
Autosomal DNA is what you inherit from each of your ancestors. Not everyone has inherited the same DNA so, for example, your autosomal DNA test might give a different result from your brother or sister’s. Using autosomal DNA tests you might be about to find people with shared common ancestry going back several generations. This assumes they have been tested and want to communicate with you! By testing relatives you can find out more. For example if your mother is tested, you can largely work out which genes come from her and which from your father (remembering that many people already share ancestry). By testing other relatives you can theoretically isolate your genetic inheritance from specific ancestral lines. This is called ‘phasing’.
So far I have spent about $200 in genetic testing and have learnt nothing to advance my genealogical studies. Part of the problem is that not enough people have been tested. Also there is no baseline for Sephardic genealogy against which to compare. Inês Nogueira has done some research on male Portuguese crypto-Jews (real, evidenced ones) and there is a project to research men of known Western Sephardic origin.
The commercial testing companies are Ancestry.com, FamilyTreeDNA and 23andMe. FamilyTreeDNA is the most popular testing company for Ashkenazi Jews. If you have an autosomal test, be sure to upload the results to GEDmatch.
A Western Sephardic Y-DNA project is currently underway. The funding comes from Avoteynu who, to my taste, are too credulous about unevidenced claims of crypto-Judaism on the American southwest. However, some reliable academics are involved, and the results should be interesting.
The Sephardic Diaspora. The Sephardic Diaspora Facebook group is the forum for serious discussion on Western Sephardic genealogy, including DNA.