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cM and % in DNA.

ProfilePosted byOptionsPost Date

ZZzzz

ZZzzz Report 18 Mar 2021 15:36

What does it mean in simple terms please, for instance if it is a bigger or higher number cM does it mean a close relationship? Can I find the connection without contacting the person, I'm just trying to narrow down who to contact as there looks like there are a lot possibilities. Thank you.

RolloTheRed

RolloTheRed Report 18 Mar 2021 16:06

The length of a piece of DNA is measured in centimorgans. The total length of all your chromosomes combined is around 7400 cM. Since a person inherits half of their DNA from each parent, you share about 3700 cM with each parent. The exact number for each parent/child relationship can vary slightly, but not by a lot

1. Confidence score 2. Approximate amount of shared centiMorgans 3. Likelihood of a single recent common ancestor

1. 2. 3.
Very high 45-60 cMs About 99%
High 30-45 cMs About 95%
Good 16-30 cMs About 50%
Moderate 6-16 cMs 15-50%

My mother in her working days was at one time sister for the gyne ward at a large London hospital. She once commented that the baby blood groups were often at variance with those possible for the putative parents. It is far from unusual for a close DNA match to have no in-common family names at all even though the geography is close.

nameslessone

nameslessone Report 18 Mar 2021 16:13

The more cms the closer you are. How high are the cms closest to you?
Has anyone with what seems to be a good match have tree attached? If so does that person match with anyone else?

I’m the iPad at the moment. As I have matches to siblings, 1st, 2nd 3rd cousins and so on I will post my cms so it will help you - soon, from the main computer.

nameslessone

nameslessone Report 18 Mar 2021 16:27

OK I am on the main computer. I am so pleased you got some good results at last.
These are how my cms go
Sibling 2000+
1st Cousin @550
2nd Cousins :@110-@220
3rd Cousin @ 50

That is just an indication of how it can go. Interestingly that big range from the 2nd cousins are all descended from the same great grandparents.

Here is the link to the Lost Cousins Masterclass - it is a big read. If you want to PM me then please do so but you might not get a quick reply :

https://www.lostcousins.com/newsletters2/aug19news.htm#DNAmasterclass&gsc.tab=0

grannyfranny

grannyfranny Report 18 Mar 2021 16:38

If the person has a tree you can view, you might be able to find a name match too, however I don't appear to have any names in common with some of my closer matches. Some of them have ancestry going way back in say the USA, with no obvious matches.
Some of the sites I have my DNA on highlight any shared names, then at least you get a chance to look at them.
I assume that folk who don't load a tree either don't want to know about any matches, or don't know the names to load.

ZZzzz

ZZzzz Report 18 Mar 2021 17:00

Thank you all so much for helping me, I have a better understanding now of how it works and am looking into it more closely now. :-D

Kense

Kense Report 18 Mar 2021 19:43

The Lost Cousins Masterclass has been updated recently.
https://www.lostcousins.com/newsletters2/mar21news.htm#DNAMasterclass