To think they are my sibling? (DNA results)

[PeanutButterFalcon]

Hello,

I have done an heritage DNA test and have been linked to someone with a 100% chance they are a close relative (niece/nephew, grandparent, grand child, half sibling).

I have looked at my family trees and there is no link that I can see to their family. If I go back further, I would imagine, our DNA wouldn't be such a strong match. Over 25% of our DNA matches and we have the longest segment length of over 150. Although I'm not sure what the segment length means.

I cannot but help think one of my parents have had an affair and they are a sibling. I have so many questions and thoughts in my head. Are these tests reliable? How would we even go about working out if we are? I cannot ask my parents if they have and I do not think they would be honest with me anyway.

What would you do in this situation?

[lottiegarbanzo]

Yes, I imagine you'd like to think the lover made her happy (happier anyway). Digging into it could reveal all sorts of tensions, difficulties and regrets though. I'd approach that with trepidation too.

Your grasp of genetics seems fine, good enough for the task. I long ago learnt a simplified version of the relatedness chart, whereby your parent, sibling or child are a 'first degree' relative, sharing 50% of your genes (on average in the case of siblings, precisely with parents and children). You multiply fractions as you go down up the degrees. So a second-degree relative is two steps away from you on the chart (grandchild, grandparent, niece/nephew, cousin, half-sibling) and half x half = a quarter, so you're 25% related to them (0.5 x 0.5 = 0.25).

What you're getting in those results is the finer scale detail, that shows that you can be more closely related to some whole siblings than to others (happened to inherit more of the same genes from the parents, or more different ones) and the knock on effects of that.

[Gwenhwyfar]

"Errr... I saw a programme about ancestry kits and they were found to not be all that accurate and the recommendation was to not bother buying them...

//www.bbc.co.uk/programmes/articles/tBX9dq9V9qWV687ddP6lK9/dna-ancestry-kits"

That article is about ethnicity/heritage not close family.

[KingsleyShacklebolt]

Exactly. Ethnicity is always a bit more hit and miss.

[KingsleyShacklebolt]

On the Y thing - the confusion is around the testing.

The tests you and your matches have done @PeanutButterFalcon are autosomal tests. They look at all of your DNA, from both your mother and father, from all 4 grandparents, 8 great grandparents and so on. The tests "decode" your DNA into the various building blocks and then look for other people who have the same building blocks as you, in the same order. Those are your matches. The more building blocks which are the same, the closer your relationship.

Men (and men only) can also opt for a Y-DNA test. Y DNA looks at a very small proportion of your DNA profile. An autosomal DNA test will look at all 23 pairs of chromosomes. The Y-DNA is only interested in one pair, which is XY in men and XX in women.

Y-DNA is very stable and doesn't change much at all through the generations. So the idea behind a Y-DNA test is to let men go very, very far back on their father's father's father's line. A match on Y-DNA tells a man that he and his match are most definitely descended from the same man, but that match could be hundreds or even thousands of years ago. Y-DNA sorts people into "haplogroups" or tribes, which gives a general indication of the migration of your ancestors from the oldest humans in Africa to more modern times.

There is also a female only test for mitochondrial DNA which looks at your mother's mother's mother. But those are less popular as there is rarely confusion over who someone's mother is.

[fuzzymoomin]

Hi OP, this is a fascinating thread. I hope you are coming ok with all of the revelations and change going on.
May I ask a question? As it seems similar to a situation currently within my family.
You mentioned earlier that the dad who raised you is now deceased, and that you have now worked out who your biological father is but have not contacted him. Can I ask, how did you work out the first was not biologically related if you were not able to test him as he isn't living now, and you also haven't test the second to confirm it?
(I'm also trying to work out a dna puzzle involving a deceased relative!)

[PeanutButterFalcon]

@KingsleyShacklebolt I bet you love your job. There’s so much depth to DNA and genetics, more than I’ve ever realised.

@fuzzymoomin I think someone mentioned on this thread way at the beginning about putting your matches into groups, so I started with that. I matched with someone I knew so that made it easier as them and all of our same matches became pink. The person I matched with did not fall into that category so not on my mother’s side. Her and our matches were blue and luckily it covered pretty much everyone I matched with. Similarly family members on my Dads side did not match with me (found they were on there a lot later in the process). Using the matches and the suggested relationship, I could build my own family tree separate to the one I thought was correct and slowly figure out how everyone was linked, it took a lot of time and dedication plus I didn’t do it alone. At the beginning I had also had my sister do a test and thought that answered everything, but I was wrong there.

[Bigfatpicnic]

@PeanutButterFalcon, thanks so much for the update. I have thought about this thread on and off over the past year, as it was fascinating. It was like you had loosened the lid on a box of secrets. I was just curious if any thing further had been discovered, and clearly it had!

You have a lot of relationship dynamics to take in to consideration with all of this and I can imagine it can be quite hard to sit on the information as you want to discover your background and family. Good luck with however you decide to move forward with this.

[Kiduknot]

Does all this affect how you view your mother? Has it affected your relationship?

[PeanutButterFalcon]

@Bigfatpicnic I’m sure there is still a lot more to find out. If I want to or not is another question. Thank you.

@Kiduknot not really. I would of appreciated the truth when I asked her but I can understand why if it’s due to an affair.

[Lochroy]

I've also been following with interest as I'm thinking of doing the test because I know my late Dad had cousins he lost touch with many moons ago and as he only has one other living relative, I'm curious to know if they had families of their own, but equally hesitant because of what else may be unearthed.

OP, the way you've managed this is incredible. I'm wondering though that you seem comfortable you are putting your mother's right to privacy ahead of your right to know more about your bio-Dad. Do you feel this because you know who bio-Dad is? Sorry if that's too intrusive and please don't feel the need to answer. I'm just curious because I think you're probably quite unique in that whilst many children will have been brought up not knowing their Dad wasn't their bio-Dad, for most, I would assume the bio-Dad would be an anonymous person from their Mother's past and so the desire to know more would be greater? I don't know. I just thinking out loud really. Please don't feel you need to answer!

[Notaroadrunner]

Could you bring yourself to just ask her if you were conceived by donor sperm, as you know that your dad was not your biological dad. She can try to come up with alternative reasons as to why you matched with these people, but at the end of the day tell her that the DNA test isn't lying.

[PeanutButterFalcon]

@Lochroy it’s not my DM I’m protecting, it’s my siblings. Until I’ve decided what I want I need to sit on it. I think if I got the answers to my many questions I’m not sure whether I would tell them or not. I also don’t think some of them would take it very well depending on the answers to my questions.

@Notaroadrunner I’ve applied to the HFEA for my information so I’ll be able to find out without asking her. They have responded to say the are taking 12months + to respond due to covid so I’m in for a wait. Also getting her alone isn’t always so easy.

[Cakeonthefloor]

On myheritage dna site my daughters, who are half siblings had a 25% match. Definitely a close relative, probably half sibling from the ages you give.

[modernfemininity]

@PeanutButterFalcon I have been interested in your story as it has played out in this thread. Can you expand on what you are protecting your siblings from now? I can see your mother might be angry if it is exposed that she had two children from an affair, although I think you cannot be certain this was an affair. She has tried to hide your parentage, hasn’t she? I am a little confused.

I know how you determined the current bio-dad dna (via a half sibling or two) but what exactly is your family make up? Feel free to alter numbers to keep anonymity but please give me the gist if you can.

Does your bio dad live near you? Did the father who raised you know?

[PeanutButterFalcon]

@modernfemininity I’m protecting them from the possible fallout it could cause. I’m waiting to see if it’s a sperm donor or an affair which I have applied for more information about. DM had many chances to tell us the truth and hasn’t.

I have a large family, we are linked to a few more families, with a range of 2-6 children in each, through one match in each however, there are matches to multiple siblings from the same family.

Bio dad not near by, however a sibling we’ve matched to is. DD did not know (as far as I know)

[Radziwill]

@PineconeOfDoom

I would do nothing, I can’t see what’s to be gained by from it. But then I would never have done the test in the first place. Non-paternity runs at about 10% in this country, and always has. Previous generations deserve their business left in the past as far as I’m concerned.

Is it really as high as 10%? I've heard MRAs use that statistic, but never anything to back it up. If a woman cheats on her partner around the time she gets pregnant, there's still a 50% chance he's the father (roughly speaking, of course -- I know it's not an exact science). Therefore, if non-paternity is 1 in 10, that means about 1 in 5 mothers don't know who their child's father is.

I just don't believe it's that common. MN is an anonymous forum -- why isn't it full of threads from pregnant women asking who their child's father is likelier to be, if 1 in 5 have at least two candidates?

[catsrus]

@Radziwill "Is it really as high as 10%? I've heard MRAs use that statistic, but never anything to back it up. If a woman cheats on her partner around the time she gets pregnant, there's still a 50% chance he's the father (roughly speaking, of course -- I know it's not an exact science). Therefore, if non-paternity is 1 in 10, that means about 1 in 5 mothers don't know who their child's father is."

10% is 1 in 10, not 1 in 5

[DeepaBeesKit]

I don't think non paternity is anywhere near that high. Most people I know either look unmistakably like their father, or have giveaway physical signs they've inherited like health conditions or unusual physical features. Maybe that's just the circles I move in.

[Radziwill]

@catsrus, that's my point. If a woman cheats on her partner, then about 50% of the time the baby will still turn out to be his. Therefore, if non-paternity is 10%, that suggests 20% of mothers were cheating when they conceived.

[KingsleyShacklebolt]

10% is way too high. According to this article it's more like 0.6% to 0.9%, so between 6 and 9 per 1000

www.kqed.org/science/11450/new-dna-studies-debunk-misconceptions-about-paternal-relationships

That seems more reasonable numbers to me.