Unexpected High DNA Match - Moral Dilemma

[farmeroman]

When I decided to go down the Ancestral DNA route I accepted that I may find something out of the ordinary regarding my parents or grandparents. As it happened I didn't, it just confirmed what I expected to find.

However, I have recently been messaged by a person with very high (the highest I have to date) shared DNA link to me who thinks that they are a first cousin of mine; they are not as I don't have any (OK, I could be wrong on that, but I very much doubt it and other factors show it not to be the case here anyway - see below).

Our common ancestors include all four of my grandparents and the age of the person concerned and the percentage of shared DNA means that they (I'll use the pronouns they/them here) could only be a child of my sibling. This person is clearly unaware of this as (I'm fairly sure) is the only person on my side of the family who could be the father.

The dilemma I have is what do I do about this? If the person concerned continues to research their DNA matches they will pretty soon determine that all of their matches include me and none include any of their father's family. Alternatively they may not understand what they are seeing, assume that no one on their father's family has been tested and give up.

Has anyone else come across this issue? Is there any accepted protocol to cover such a situation?

[PaulineJ]

what was the situation with this person's parent(s) at the time of their conception?

if the man stepped in to do the decent thing it's a bit less shocking than adultery...

[farmeroman]

what was the situation with this person's parent(s) at the time of their conception?

if the man stepped in to do the decent thing it's a bit less shocking than adultery...

I don't know the situation, but I doubt very much that it was planned that way.

[decor]

As soon at this person does a bit of research into centimorgans, they'll have proof that you can't be their first cousin as the numbers are just too high. And perhaps soon after they'll realise they matches don't "match" with their expectations.
I think if I was in your shoes, I'd try to formulate a polite message to send to them, explaining that the cMs mean only one thing.

[Gadget]

Would you be able to share with us the shared cMs and the age difference between both of you.

I have a case of a 3rd cousin where the shared cMs is more like a 2nd cousin.When I investigated in more detail - I found that we  were related by 2 separate lines.

[majm]

Perhaps they already 'know' but are using the word 'cousin' at this stage for politeness, discretion. ... Afterall this is their first contact with you, ...  so perhaps they are as careful as you, and are worried in case you may not be aware of the significance of  that high reading.

JM

[farmeroman]

Would you be able to share with us the shared cMs and the age difference between both of you.

I have a case of a 3rd cousin where the shared cMs is more like a 2nd cousin.When I investigated in more detail - I found that we  were related by 2 separate lines.

A little over 25% shared DNA and around 1800cM. Age difference around 25 years.

Ancestry says "Close Family – 1st Cousin", although that is then contradicted by "Possible DNA relationships" which says that "100% of the time people with that profile are":
- grandparent
- grandchild
- half sibling
- aunt/uncle
- niece/nephew

The first three are not possible. Uncle (me) and niece/nephew (them) is the only possiblility in my opinion.

[farmeroman]

Perhaps they already 'know' but are using the word 'cousin' at this stage for politeness, discretion. ... Afterall this is their first contact with you, ...  so perhaps they are as careful as you, and are worried in case you may not be aware of the significance of  that high reading.

JM

I can't 100% rule that out, but judging by their lack of knowledge regarding DNA I don't think so.

[Gadget]

A little over 25% shared DNA and around 1800cM. Age difference around 25 years.

Ancestry says "Close Family – 1st Cousin", although that is then contradicted by "Possible DNA relationships" which says that "100% of the time people with that profile are":
- grandparent
- grandchild
- half sibling
- aunt/uncle
- niece/nephew

The first three are not possible. Uncle (me) and niece/nephew (them) is the only possiblility in my opinion.

I have around the same amount and age difference with my niece

on Ancestry - 26% and 1846cM