Concepts: What are NPEs and MPEs?

Child with helix

Sooner or later in genetic genealogy, you’re going to run across the acronym, NPE or MPE.

Years ago, the phrase NPE was coined to generally mean when the expected parent or parents weren’t.

  • NPE means nonpaternal event, also sometimes nonparental event.
  • Some folks didn’t like that term and began to use MPE, misattributed paternal event or misattributed parentage.

Of course, today, this situation could arise as a result of an adoption, a donor situation, either male or female, or the more often thought-of situation where the father isn’t who he’s presumed/believed to be based on the circumstances at hand.

Historically, adoptions weren’t a legal situation. If the parents died on the wagon train, someone took the kids to raise. Ditto a woman raising her sister’s children.

At that time, everyone knew the situation and it wasn’t a secret. A couple (or more) generations later, no one knows and the presumed parent(s) aren’t, especially if the child used the surname of the people who raised him or her. That’s a very common step-father situation, especially before official birth certificates.

Regardless of the situation, the “adoption” was undocumented for future generations. Hence, the term “undocumented adoption.” I’ve used “undocumented adoption” for a long time because I felt there was less judgement inherent in that description. Other people simply say “of unknown parentage.”

Discoveries are Common

Of course today with various types of DNA testing, these types of situations are slowly, or not so slowly, being discovered.

When they reveal themselves, you may have to saw a branch off of your tree. That’s ugly if you’re a genealogist, but at least it’s not someone you know personally.

However, if the people involved are closer in time, the discovery may be a shock or traumatic. I experienced this with my half-brother, Dave, who turned out not to be my biological brother.  I found him and then heartbreakingly lost him. I loved him regardless and wrote about our journey here, here and here.

These situations used to be remarkable, but with so many people DNA testing, these revelations are becoming daily events.

No Judgement

While the first thought that might occur is that someone was cheating, that may not be the case at all. Lots of circumstances may come into play. I wrote about several here.

I would encourage everyone to suspend judgement, not assume and to give our ancestors and family members the benefit of the doubt. We don’t and can’t know what happened to them.

Moccasins and glass houses😊

Besides that – if it wasn’t for your ancestors, you wouldn’t be you!



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40 thoughts on “Concepts: What are NPEs and MPEs?

  1. Hi Roberta, I believe I have an NPE but would like some assessment from someone better than myself regarding this, can anyone please advise

  2. I’ve done an in-law’s genealogy tree back to early 1700s, only to find there was an illegitimate son in the direct male line [call them P’s]- which many of the family know about. But my in-law’s mother’s line also shows an illegitimate son back to the same period – and I’m certain they don’t know about this. So if the maternal line, call them A’s – if the male A’s test, they won’t have the right DNA for their surname. And if the paternal P’s test, neither will they. I’ve put a strong note on one of my blogs about the male P’s, that they won’t test out as P’s in a Y-DNA test. Haven’t done the same for the A’s yet. And the families aren’t living anywhere near here, aren’t terribly close either. I dread them doing DNA tests and being surprised at their results… 🙁
    Thank you very much for the several heart-felt articles you’ve written on these unknown parentage events – I appreciate it very much.

  3. Roberta,
    Awesome article definitely loved in. I looked at this way my Grandmother could have given my dad up for adoption but instead chose to keep him…grant it she told some whoppers about who his real father was but I found him. Even so with that said still love my Grandmother and your right I wouldn’t be here if she had given him away. I am whom I am because of my ancestry. Awesome article…thanks


    Cindy Carrasco

    • I just view them at this point as “colorful” and interesting because the only control I have over the situation if how I perceive it. I do have an ancestor who was murdered by her husband and I struggle with that one. There’s no way around that.

      • Wow…I really don’t know what to say to that. I guess you never really know what your ancestors are really capable of definitely.

  4. When I looked at this title it occurred to me that many of us use acronyms but many more have no idea what we are speaking of. Have you ever done a blog on acronyms in genealogy?

    • No, I’ve never really thought about that before. I wonder if some terms mean different things regionally or in different contexts.

  5. Well said, indeed. From my own experience, it pays to be circumspect. When my mom’s paternal line 3rd gg turned out to be the son of a neighbor (strong aTDNA and YDNA proof + solid genealogical records), we nontheless proceded cautiously because in this name-proud Scottish line there are a half dozen living men carrying his very distinctive three name moniker.

  6. I have a first cousin, almost certainly the previously unknown son of my late uncle. He tested on Ancestry several years ago, but has never responded to any of my messages. His son has tested with several companies and is now on GEDmatch so I have an email. He posted a partial family tree and, being the good genealogist that I am, I was able to find a public record DOB. I have a pretty good of the circumstances around his conception. I don’t want to sound like a stalker and I am having a hard time deciding what to write in an into letter. Maybe just “welcome to the family”?

  7. “Moccasins in Glass Houses”? I’m not familiar with that saying. Huh.

    So sorry about Dave, Roberta. =( It sucks to find someone and then lose them. At least his story is immortalized here in the blog.

    As far as NPEs go, I have at least one that I know of. Dealing with that was interesting as I was the go-between between my great-aunt who found out she had a half-sister and a half-cousin and the half cousins. I was so concerned that I rocked the boat when I discovered this. My great-aunt, who is 95, told me not to worry about it. “It is what it is”.

    She also said it was kind of expected. So, we just kind of deal. From what I understand, the half-sisters talked on the phone a few times. Not sure what the status of everything is now.

    Just was kinda scary and daunting going back and forth like that.

    • It was a play on words without saying two phrases completely. Don’t judge someone until you’ve walked a mile in their moccasins and people who live in glass houses shouldn’t throw stones.

      • I get it. Thanks. =) I’ve just finished reading the other blogs about Dave. He sounds like a cool guy. I would also protect animals like he did. And people. Not going to spoil the story here. But, it is quite an epic tale.

        Thanks for sharing it! =D

  8. “Moccasins and glass houses” – love that. May I borrow it sometime?… (with proper credit, of course).

  9. I don’t recall hearing about any MMEs – misplaced maternal events with an in-vitro donor egg. Have you? Has anyone written about this? Or is it too rare? Just wondering!

    • No, I haven’t. What I have heard about is the first wife died and the child was from the second wife, or vice versa. In one case, it wasn’t even known that there was another wife.

  10. My/Our Daddy met our divorced mom when she already had four of us kids. Paternal parent had disappeared. We lived in New York on Long Island. Daddy was in NY for his brothers wedding. He and mom met in a hangout/bar.
    He came to meet us soon after.
    I can honestly say that when that shy, beautifully smiling man ducked his tall frame and shyly peered his gorgeous smiling face around the door to Moms ‘Come in’ after he knocked, my immediate thought was ‘Please God let him be my Daddy’!
    And so he was. His was ‘Daddy’ the next day.
    Daddy was part Native American, 6’2” with a huge smile, thick black wavy hair and a small gap between his two front teeth. His big brown eyes didn’t miss a trick and mostly twinkled.
    He grew up in the South in ‘Welfare Homes’ the precursor to foster homes. We quickly learned that those families loved him after moving to Va to visit them.
    Daddy could do almost anything. He could also tame any critter or child with ease.
    He very quickly adopted us. My only complaint was that I was told that the judge would ask if I wanted him to be my Daddy, (I’m the eldest)
    That judge didn’t ask.
    However, I do remember hanging onto Daddy and glaring at the judge as if daring him to say no.
    Daddy and our mother had eight more children.
    We had a small farm by then thanks to our grandparents who immediately absolutely loved and adored their new son-in-law.
    My Daddy was the best man I’ve ever known besides my own son who learned his carpentry/masonry trade and so much more from working with his hardworking Grandpa.
    Yes. We were blessed.

    As we have always heard – blood is thicker than water. However, we also know that love is thicker than blood.
    I have additional proof many times over. Our grandparents had adopted our mother.
    My grandparents and Daddy were absolutely the best blessings in my life until I had my own two now grown children and now two precious young grandchildren!
    Life is good!

  11. I have an NPE on Dad’s side. Evidently it was his father, an orphan, a ‘foundling’ etc. No one in the family expect perhaps my Mom, knew and of course all that is long gone. The question is, all these folks are showing up as DNA 2nd, 3rd cousins and on down, pointing back to a common ancestor. Is there a way to narrow down which of his sons was the likely father of my Grandfather? I tested my Y when National Geographic first came out, never got a Smith hit, but I did with Deal, way back, which is why I think it was the male line.

    • Use a combination of Y DNA, autosomal DNA and I would suggest the Leeds method. One group of 4 will be unfamiliar to you.

      • Thank you Roberta. I looked up the Leeds method just now, found your paper on it and will be busy tomorrow! Thank you so much! I’ll follow up when I do. I love the puzzle! Dave

    • Use a combination of Y and autosomal. You may match some people on both. Or, walk the matching segments back in time.

  12. I prefer MPE or “brick wall”. In genetic genealogy a lot of guidelines have not evolved as yet so I refer back to genealogy practices one of which is do no harm. MPE to me is a more appropriate term for an unknown. I will also add in 31 years of genealogy research I have never used the term ” illegitimate son”.

  13. Loved your explanation of the other side of our family…i.e. adoptions or finding people in your tree you have no idea how they came about. A great example of the wagon train crossing and the sister to a sister (or brother to brother) just automatically took the child in question into the family fold. Humbling. Thanks

  14. As soon as my mother and I received our DNA results, we discovered a NPE. He turned out to be a son of one of my mother’s first cousins. That first cousin had a twin brother. I know that identical twins have exactly the same DNA, but do they always look alike? My mother remembers, and photos show, that they were very different in appearance. One of the twins is now deceased, and the other is elderly and not well (his daughter matched as a half-sister). There will be no further investigation, but I keep wondering whether we can make an assumption as to paternity?

    • The only thing that would help us if the children of both men tested. If they are not identical twins, the child will match one closer than the other.

  15. I also have a experienced an MPE event when researching my husband’s family. I found his 2G-grandmother was adopted, so all the work and research on her adopted family pretty much for naught. I do know however, that her last name was “Rose” – and through DNA testing of 2 of her g-grandsons, and 1 g-g-granddaughter, that I feel confident I know which Rose family she came from – but I’m no closer than that, I’m not even sure which generation she came from. How much Rose DNA would she pass on to her great-grandchildren, or g-g grandchildren ? would that help me to at least determine the generation?

    BTW – love your blog 🙂

    • She would pass approximately 12.5% to her great-grandchildren and half of that to the next generation. I’m reality, it varies slightly.

  16. The Jotham Brown line would appear to be responsible for an NPE, based on new Big Y-700 results. A member of the Barber family has long suspected a 19th century relative was actually a Brown. A recent Y-37 test showed him close to descendants of both Jotham & Abraham Brown, and Martin Voorwinden suggested Big Y might clarify the situation. Results received Thursday match results provided by two of Jotham’s descendants — Y-FT126417!

  17. Pingback: Concepts: Chromosome Browser – What Is It, How Do I Use It, and Why Do I Care? | DNAeXplained – Genetic Genealogy

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