Active discussions

Meet the Other Phone. Flexible and made to last.

Meet the Other Phone.
Flexible and made to last.

Buy now

Please or to access all these features

Talk
Chat

Join the discussion and chat with other Mumsnetters about everyday life, relationships and parenting.

Original poster

My heritage dna results, share 38% dna with my sibling

26 replies

Whatayear21 · 03/04/2021 16:14

So me and my sister took a my heritage dna test because my Dsis remembers my DF saying that we are not all his children one day in a drunken rant.
The results are back saying me and Dsis share 38 percent dna, which I know is possible for full siblings, but my Dsis read about 3/4 siblings, which basically means that our fathers could be brothers. 3/4 siblings share around 37.5% dna and full siblings on average around 50% dna.
She's convinced this is the case.
Anyway I know i'm probably overthinking this and we are in fact full siblings. But I just can't shake the thought since she mentioned it! It doesn't help that my dad and his brother were completely no contact and wouldn't tell us why.
So am I being ridiculous and we are in fact full siblings? Has my Dsis got it completely wrong?
Both our parents are dead by the way so we can't ask them about it.

OP posts:
ElizabethG81 · 03/04/2021 16:31

I share 36.5% DNA with my full sister, and my children (full siblings) share 39.7% DNA with each other. 50% would be at an extremely high end for full siblings, it's more like the match that you have with a parent/child. I think you're overthinking it because of what your dad said, it looks like a full sibling match to me.

Original poster
Whatayear21 · 03/04/2021 17:11

We probably are overthinking it!
And that's reassuring, although it definitely is an average of 50 percent you share with a full sibling. Can fall outside of that range though.

OP posts:
ElizabethG81 · 03/04/2021 17:16

It usually falls lower than 50%, because although you get 50% DNA from each parent, each sibling will have a different 50%, meaning that the actual amount of shared DNA ends up being lower.

This is a good tool I use - dnapainter.com/tools/sharedcmv4

Put in either the cM match, or the percentage, and it shows you what the possible relationships are. The normal range for siblings to share is between 1613-3488 cM. My children share 2734 with each other, I share 2500 with my sister.

Interested in this thread?

Then you might like threads about this subject:

Families
Einszwei · 03/04/2021 17:19

Agree with PP. Use Centimorgans and put into DNA painter.

DontBiteTheBoobThatFeedsYou · 03/04/2021 17:21

I would be over thinking it too, anyone would - thanks Dad!

Is there any way to find out for sure?

Original poster
Whatayear21 · 03/04/2021 17:36

I have looked at the dna painter and it takes full and half siblings into account but not 3/4 siblings by understandably.
It probably is the case that we are full siblings.
I don't know anyway to find out, other than asking my uncle who is still alive, bit don't want to look like a psycho as we don't have any contact, only at funerals etc.
After doing my own research we could be full siblings, full siblings will fall between 37 and 61 percent with an average of 50 percent, half siblings 25 percent and "3 quarter siblings" average at 37.5 percent.
I know i'm thinking too much now! And probably need to stop lol.

My heritage dna results, share 38% dna with my sibling
My heritage dna results, share 38% dna with my sibling
OP posts:
Original poster
Whatayear21 · 03/04/2021 17:39

We share 2753 Cm
Shared segments - 40
Largest segment- 144

OP posts:
GhoulWithADragonTattoo · 03/04/2021 17:44

What do you mean 3/4 siblings? Surely you can either share both parents (full) or one parent (half).

ElizabethG81 · 03/04/2021 17:44

Are there any other close relatives on there that you could compare yourselves to?

Someone more skilled than me in it would probably be able to get you a more definitive answer by looking at the detailed information on the chromosomes.

ElizabethG81 · 03/04/2021 17:47

@GhoulWithADragonTattoo

What do you mean 3/4 siblings? Surely you can either share both parents (full) or one parent (half).
It's if siblings share, for example, a mother but have different fathers, but the fathers are brothers. So they will share a lot more DNA than half siblings because the 2 fathers will also share DNA.
Original poster
Whatayear21 · 03/04/2021 17:50

A 3 quarter sibling is someone you are both half siblings and also cousins with, so would happen if you had different fathers that happened to be brothers (same story for mothers that could be sisters)
It's probably not the case!
There's no other close relatives on there to compare to unfortunately.
My sister who I have compared dna with is a non identical twin, so she (my other sis) is going to take the dna test to see if me and her also match at only 38 percent and to see if her and my other sis match at 50 percent, but takes around 8 weeks for the results!
All the numbers are hurting my head now! Lol.

OP posts:
Original poster
Whatayear21 · 03/04/2021 17:56

None*

OP posts:
4Mongrels · 03/04/2021 18:04

Has your uncle got any children that would test, or would he?

Bellyups · 03/04/2021 18:15

I haven’t used my heritage, so probably not overly useful to you, but I have used AncestryDNA. On this, my full sibling is coming up as 45%-52% shared DNA.

SwedishEdith · 03/04/2021 18:23

Did he say "we are not all (of) his children"? I'm reading that as he may have more not that he's not your dad.

DivGirl · 03/04/2021 18:27

@Whatayear21

We share 2753 Cm Shared segments - 40 Largest segment- 144
Based on these numbers I’d be pretty confident in saying you are full siblings. The only definite way to find out though is to test the uncle.
ElizabethG81 · 03/04/2021 18:37

@Bellyups

I haven’t used my heritage, so probably not overly useful to you, but I have used AncestryDNA. On this, my full sibling is coming up as 45%-52% shared DNA.
I'm on both, and find the % Ancestry gives really confusing, as it's not the actual % if you go off the cM. OP - don't let this throw you off, the sibling matches I've discussed upthread show a higher % on Ancestry than they do on My Heritage. It's best to go off the cM.
Notaroadrunner · 03/04/2021 18:37

Sharing 50% DNA is just the average so sharing 38% is perfectly reasonable. You share quite a high amount of cm's for a full sibling, so I would imagine you are indeed full siblings.

Original poster
Whatayear21 · 03/04/2021 18:40

swedishEdith his exact words were "you're not all mine anyway"

OP posts:
2021mumma · 03/04/2021 18:41

I share 50% DNA with my Dad so I would say 38% would sound as though she is your full sister

SwedishEdith · 03/04/2021 18:43

@Whatayear21

swedishEdith his exact words were "you're not all mine anyway"
Ah, okay. I can see why this would be playing on your mind.
4Mongrels · 03/04/2021 18:57

The amount of cm you share would be high (although not impossible) for 3/4 siblings and is indeed higher than the average match for full siblings.

A DNA test on your Uncle or one of his children would be the only way to tell for sure but I would put my money on you being full siblings.

TwoLeftSocksWithHoles · 03/04/2021 19:10

Well that's a relief, on an initial perusal of my own, it seemed I was more than 60 % penguin.
I must admit I don't really feel the cold...

Original poster
Whatayear21 · 03/04/2021 21:11

Well this is all very reassuring! Thank you

OP posts:
PainterInPeril · 04/04/2021 10:56

Maybe he meant that you are your mother's children too. As in, you get some of your looks or personality traits from her. (Obviously I don't know the context of his rant.)