DNA may not lie, But it sure is confusing

Example 1: I was watching a TV program about a woman who was going to give up her child to her sister who is unable to bear children. This got me thinking about the child’s DNA and how we might end up interpreting them.

Let’s say the Child has their DNA tested and they are the oldest generation living. Thus, what assumptions might we come up with from his test. If the child didn’t know they were adopted, would they figure out they were adopted.

His legal/adopted mother is the sister of his biological mother. Thus, his DNA results on his mother’s side would appear to be the same and no real unexpected results because his maternal side is the same with either mother. However, it may appear that his legal/adopted mother had an affair because his legal/adopted father’s family would not be showing in his DNA results. Also, what if his biological mother did not have any more children, thus we would not know that his legal/adopted mother is not his biological mother since neither woman had any additional children to find half siblings or descendants of those half siblings. Even if his biological father had additional children, this would not make his maternal DNA any clearer.

Moral of the story, even though DNA doesn’t lie, it might not be so straight forward. We need to always remember these outlying relationships and not judge our ancestors so quickly.

Example 2: I had a former co-worker who adopted her 1^st cousin’s child. Again, I was thinking about the Child’s DNA and how we might end up interpreting them. Her 1^st cousin’s mother and her mother are sisters. Again, let’s say the Child has their DNA tested and they are the oldest generation living and they don’t know they were adopted.

Let’s look at his legal/adopted mother’s DNA compared to his biological mother’s DNA. Both women share one set of grandparents through their maternal side of their family. Thus using the Leeds Method, we may find that the tester’s maternal grandmother’s side of the family matches correctly, however he has three grandparents that are not matching any known relatives, his father’s side (his father's parents), and his maternal grandfather’s side.

Thus, why might this happen? Did his mother have him with another man than his father? Did his grandmother have his mother with another man? The test might show that one branch, his maternal grandfather’s side appears to be matching his grandmother’s brother-in-law’s family. Did grandmother have an affair with her brother-in-law? See how easy it is to jump to the wrong conclusions. We need to test our theories.

This is where testing closer known relatives come in handy. Did his legal/adopted mother have any siblings who had children? If so, do these matches appear further away than expected. Did his biological mother have any other children and did they happen to test and are showing up as half-siblings. Did his biological mother have siblings who have children. If these people didn't test, we may need to seek out these types of relatives and ask them to test.

Moral of this story, again, DNA isn’t always straight forward. We need to let the DNA tell the story. Testing as many close relatives as we can helps us develop a clearer picture. Not only our maternal first cousins (in this case), but maybe his mother’s first cousins or their children (his 2^nd cousins).

A wonderful website to help with our confusing DNA matches is DNAPainter. Their Shared cM Project 4.0 tool has a handy chart to show where matches should fall into. In my 2^nd example, who we think should be his first cousins (children of his adopted mother's siblings) are really his 2^nd cousins and the shared DNA between 1C’s and 2C’s is very different.

Good luck in your DNA research and explore all the relationship possiblites to help in your DNA research!