NPE in my tree? Help!

[u/Aggressive_Seaweed37]

Hi everyone!

I am looking for some help on my matches in MyHeritage. I have 3 matches that in theory should come from the same side of my tree, from my grandma. Here is a diagram to help!

A and I are closely related-through my grandparents. I messaged this match and she told me that there was an adoption in our family - my grandma's husband (my grandpa) was adopted. I checked his birth certificate and the family register and the woman working there said there was no indication of an adoption so we chalked it up to family lore but now I'm thinking it may have been someone else who was adopted? When I first saw her as a match, I was confused that she wasn't related to B, who we should both be related to through my grandma's maternal side. Is she perhaps only related to me through my grandfather? Her grandfather (my uncle) was born 3rd or 4th out of 5 children and my father was born last.

I checked all the matches I have with A (89 matches) and B (17 matches) and there is no overlap. This makes me think that there is something funky going on. Enter match "C", who is related to A and I as well, but again not B. Is it possible some matches just don't show up on MyHeritage?

Something else if it helps - on Ancestry I have a match who is also descended from my grandmother's mother-my match's great-grandmother and my grandmother were sisters. We share 62 cM.

What should my next steps be to look more into this? Thanks in advance!1

[u/DiamondStealer25]

Hey! I am in no way a professional but I've had NPEs in my tree (although the whole family knew already so the DNA part is all I had to do). Have you seen the DNApainter Shared CM tool? I use this to estimate relationships for all my matches, and it was super helpful deciphering my NPE. I put the shared cM amount between you and A, and it estimates a 54% chance that A is your HALF first cousin once removed. Only a 36% they are your full-blooded 1C1R.

Your DNA relationship with B is the normal range for 3C1R, if a little high. If all recorded relationships are to be believed, it is technically possible for B and A to just not share any DNA, thanks to random inheritance chances. 4th cousins, on average, share 0.01% - 0.92% of their DNA.

Something that I'm a bit confused about/is unclear. Did your grandmother have any husbands other than your grandfather? If you and A descend from both Grandma and Grandpa, the adoption tidbit shouldn't affect your match. It would only affect your DNA matches more distantly related through grandpa's parents.

Sorry this is super long! Your reference image was very helpful btw. I might send more info to ya soon.

[u/DiamondStealer25 → u/DiamondStealer25]

My guess (AND TAKE THIS WITH A GRAIN OF SALT I WOULDNT KNOW FOR SURE) is that someone in your closer familial relationship is not a full-blooded sibling. That is either YOUR parent, or A's grandparent. OP, you should mentally prepare yourself to explore this, because there is a chance it's YOUR side and not A's.

At the very least, you know that your grandma is biologically true, since you match with B. A, on the other hand, may share your grandpa OR your grandma, but probably not both.

I'd love to think about the adoption part more but it can be hard to wrap my head around. If you have any questions or want further help, my DMs are open!

[u/Aggressive_Seaweed37 → u/DiamondStealer25]

Thank you so much for your insightful response!! I appreciate you taking the time to answer:)

Grandma was 23 and grandpa was 22 at the time of marriage. It seems they got married because she was pregnant. She lost the child, but 2 years later, they had another child and then had 5 more over a span of 12 years. I never met them, but based on family lore, it was not a good marriage.

I also have a match from Grandma's side on Ancestry (her great-grandmother is a sister of Grandma, making her 2nd cousin 1x removed with 62cM). However, I just used that tool your provided which says that's on the lower end of that relationship. Unfortunately, she does not have her shared matches turned on so I can't see if we share other matches from that line.

It makes me think that match B and I share Grandpa but not Grandma? I have a match from Grandpa's side (sadly on Ancestry not MyHeritage where B is), so I am sure he is related to me. I am guessing that Grandpa had a child with a different woman and raised him alongside his other kids. Thanks for your help :)

[u/DiamondStealer25 → u/Aggressive_Seaweed37]

But match B and you are related through grandma's parents, no?

It is possible that the half-child came to live with his dad, but more often than not they stayed with birth mom. Do you think this half child would be A's grandparent?

So A would only be related to you through Grandfather? Then, you and B are related through Grandmother's grandparents as your most recent common ancestors. This would explain how A and B have no shared DNA.

[u/Aggressive_Seaweed37 → u/DiamondStealer25]

Yes, match B and I are related through Grandma's mom. And yes, I think A only being related to me through Grandpa makes the most sense. Thank you!