Adopted and making sense of my DNA matches: which are paternal vs maternal?

Question

I am adopted. I know who my birth mother was and that she came from France. I was conceived in a Brothel in a small town that ironically, my adoptive parents lived only miles from, and that I raised my family in! So many of my matches of distant relatives are people I've known all my life!

I do not know who my birth mother's father or mother were or who my father was. I have lots of matches and have done a triangulation on Gedmatch.

I'm super confused. 75% Spanish Basque, Scottish, Irish, Russian, Jewish, Sardinian, Great Britain make up the rest. Where is the French?

I have found two second cousin matches and four 3rd cousin matches, and 35 4th cousin matches with almost all matches being Spanish Basque.

Which side is my birth father's side?

This has been my life's quest, searching for my family. Searching for my birth father.

Now, with DNA, I thought I could find him, but it's confusing to figure out which side is which?

How do know if these cousins are mine because maybe my birth mother's father is the common ancestor?

Answer 1

Unfortunately it's not possible to determine which side of the family all your DNA matches are without phasing. In order to phase your matches completely, you need to have either your mother or father, or another close relative, also test – which it sounds like is not possible in your case.

The problem why you cannot identify a certain match as maternal or paternal is because the DNA test does not sequence the chromosomes. Instead, key points in the genome are tested - single nucleotide polymorphisms (SNPs). Essentially, for each SNP, you are going to have two nucleotides (A, C, T, or G). At a given SNP, your result might be CT – the C came from one parent, the T from the other. However there is no way to tell whether the C is from mum or dad. By testing a parent or close relative, you can determine which matches come from which side of the family. For more on phasing see the ISOGG Wiki.

Certainly follow up with your DNA matches to see what relatives they had in your particular locality, but this will obviously be difficult.

I would start with trying to research your mother's family first, because you have something to go on. Even if it's just a name, it's something to go on. Finding her birth record should lead you to her parents. I would speak to local archives to see what records are available (I suspect many containing information on living persons may be restricted access). If you can narrow some of your DNA matches to your mother's side, then that's a start.

I would not get too caught up on the ethnicity estimates; you have to treat the results with a grain of salt. For example, my results from one company say 10% Italian, yet I have traced all my lines of ancestry many generations back (most at least to early 1800s), and yet to find an ancestor born outside of England.

Finally, you did not state which company you tested your DNA with, but if you have not already done so, I would encourage you to transfer your data to all possible sources – Gedmatch, FamilyTreeDNA, MyHeritage. All of these companies accept free transfers – free matches with other cousins. Gedmatch has a number of tools which can be helpful with triangulating matches.

Best of luck in the search, keep in mind that you will get additional DNA matches over time so it may just be a bit of a waiting game until the key match turns up.

Answer 2

A single person's DNA alone (yours) cannot tell you who you're related to (other than in a vague, very distant, ethnic sense, maybe). If you have close enough matches with people who know a good deal about their extended family and ancestry, it might be possible to combine that with other knowledge to get closer to an answer. If your second-cousin matches are from distinct branches, it may be possible to get some hint about your ancestry if they are cooperative and have family knowledge. Second-cousins are close enough that some narrowing of possibilities might be possible. It would take a good amount of study and research of their relations, and results might be minimal.

If the 75% Basque results are reliable, it indicates Basque heritage on both sides. A likely scenario is that one parent was mostly or all Basque, and the other parent was half-Basque, but other mixtures are certainly possible. In any case, there is no indication of which parent had the greater Basque heritage.