My daughter just learned she shared 314 centimorgans with a boy we believed was her half brothers son. I have just sent in my sample as the supposed father of her 50 year old half brother.

We are all stunned and embarrassed by our ignorance. I guess I need help because if my daughter in not the young man's half nephew how can I be the father of her half brother?

Am I in for more surprises?

I am not to good at all this and perhaps am not making it clear.

For 46 years I was told this person was my son. It happened when I was a teenager and before I was married. No blood test but just believed what I was told.

Now out of the blue my daughters are on 23andMe and a name pops up linking them as possible 1cousin1removed or second cousin. It was the son of the man I am supposed to have fathered.

My daughters 314/325 centimorgans took them out of the half-Aunt catagory.

I sent my DNA in and it came back 999cMs. Telling me I was his great Uncle.

My question is if my daughters aren't half-Aunts how can I be the boys grandfather as the story that has been told for 46 years.

Doesn't the cMs puzzle have to fit for all relationship categories?

I am new to this and don't grasp it well.

  • 1
    I'm a little confused - 314 cM isn't a likely match for a half-aunt, so I don't understand why you believed the matchee was her half-brother's son. It's difficult to answer the question without some clarification.
    – cleaverkin
    Commented Aug 8, 2020 at 18:14
  • 1
    This question will be more answerable when Rob gets his results and can edit the question to add the cM shared with daughter and with the son of the supposed half brother.
    – shoover
    Commented Aug 8, 2020 at 20:47
  • This is why I need help. I am baffled by all this new information first of all and we believed the story that the boys father was a half brother to my daughter. This is why we believed he was a half nephew. However both my daughter and the supposed nephew took the 23andMe DNA test and he showed up connecting to my daughter with 314 centimorgans. This is all over my head at the moment so I thought I would ask a group who understood it better than me at this point. So if this boy isn't a half nephew then she also doesn't have a half brother. Am I correct?
    – Rob
    Commented Aug 9, 2020 at 1:31
  • Cleaverkin... I have been ignorant about centimorgans my whole life. I just believed the story that was told me... I got a girl pregnant in my teenage years. Now 46 years later this half-brothers son shows up as sharing 314 centimorgans with my daughter. We are all stunned and embarrassed by my ignorance.
    – Rob
    Commented Aug 10, 2020 at 20:48
  • 1
    There's a handy cM lookup tool on the DNAPainter website: dnapainter.com/tools/sharedcmv4-beta I realize this will become more clear when your test comes back, but looking at the numbers, I have to ask - did you have any brothers back when?
    – cleaverkin
    Commented Aug 11, 2020 at 19:34

4 Answers 4


It seems like the child that you thought was yours is actually your half brothers son. And the boy is your daughter’s Half 1st cousin 1x removed. I have half siblings so your DNA resembles those of my family.


According to DNA Painter's shared cM tool, the following relationships for 999 shared cM have a 100% probability of being true: Great-Grandparent, Great Uncle, half Uncle, 1st cousin.

Given your story and the generational difference between yourself and the boy in question, the most likely relationship between you two is Great Uncle - Great Nephew. So your relationship to his father is Uncle-nephew.

Shared 314 cM suggests a wide range of relationships, including 1st cousin once removed (39% probability), which, given your known relationship to your daughters, is their most likely relationship to the boy in question. Their relationship to his father is 1st cousins.


Another possibility is one of your uncles is the father and you are the 1st cousin to the kid that you thought you fathered.

start testing them could be from your moms or dads brothers.

test your parents and find out which side its coming from


DNA doesn’t lie. If not your brother’s child, maybe it is an uncle’s. I have a first cousin (our mothers are sisters) who I share 850cM with.

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