adoption and DNA am I making the right conclusion?

[VivienR]

I know that my 2x great grandfather was adopted. 

I was just looking at my DNA matches and found I had a match with the adopting father and one of his sisters.  The common relatives were the parents of this brother and sister. So do you think I can conclude that my 2x great grandfather was a grandchild of the common relatives and that one of the adopting fathers siblings was a biological parent.

It would seem most likely that this would have happened as the adopting parents didn't have any other children and the adopting father had a large family of brothers and sisters.

Still trying to wrap my head around this and hope I have managed to describe this clearly. I just can't think of any other reason why I would have a DNA match with the adopting father.

Thanks for any input you can give me on this.
Vivien

[sugarfizzle]

It sounds a reasonable assumption, but as ever with DNA, you cannot 'conclude' that your workings out are correct. You are fairly obviously genetically related to this family, but there is a possibility that it is from a different branch, a generation further back, though perhaps unlikely. That is, the adoptive father adopted not a niece, but a cousin's child.

Are matches with the adoptive father and his sister showing at around the same level? If so, perhaps concentrate on finding out who the other siblings married, and their children etc, see if any other matches come up with these surnames. Eventually you might find a DNA match from this family at a closer level.

Had you followed this family before, did you think the 'adoptive' mother was the real mother and followed her tree? Or did you go no further than the pair of them?
I'd be interested to know how you approached this from a non DNA point of view.

Best of luck

Regards Margaret

[whiteout7]

How many centimorgans of DNA do you share?

You are clearly related to them but how is the puzzle?

Chart
http://thednageek.com/the-limits-of-predicting-relationships-using-dna/

[VivienR]

Hi Margaret

I have started tracking down the adoptive father's siblings and their families to see if there was a missing child somewhere but no luck yet.  The match with the adoptive father and the sister were at the same level which lead me to believe that perhaps he had adopted a nephew.

 My dad is from Quebec so there are lots of big families but thankfully the Catholic church kept good records. I have done a lot of research on my dad's side of the family and I do have a fairly extensive family tree but just hadn't found a connection to that particular Gagnon family before other than through the adoption.

I did find a DNA match yesterday with the adoptive mother but it wasn't as close a match as this one. I had traced her family but hadn't added her siblings to the tree. 

The difficulty is that there were a small number of families that came to New France and so it's really not surprising that these families would be related on one way or another.

Feels a bit like a needle in a haystack search but I have gotten through some brick walls lately so I am hopeful for this one.

Thanks for your reply.

Vivien

[VivienR]

How many centimorgans of DNA do you share?

You are clearly related to them but how is the puzzle?

Chart
http://thednageek.com/the-limits-of-predicting-relationships-using-dna/

Thanks for the link.  Yes I am dealing with a small group that intermarried over mulltiple generations so that makes things more difficult.  I was wondering how accurate these DNA matches could be.  Not as accurate as I had hoped.

Vivien

[sugarfizzle]

If you are talking about an endogamous community, the problem is compounded.

One of my cousins who I was in touch with before DNA testing has an American with British roots father, and a Hawaiian mother. Unfortunately we are not a DNA match.

Whereas I have thousands of 5th to 8th cousins, she has thousands of apparent 4th to 6th cousins and closer, her 4th cousin list didn't start till 32 pages, approx 1600 apparent 3rd cousins and closer.

Needless to say, not many of them are true close cousins.

Regards Margaret