Half 4th cousin

[LizzieL]

Does anyone know how I can work out the likely range of cMs match I would have with a half 4th cousin, please

[TreeDigger]

Hard to say..

The upper end would most likely be somewhere around 60-65cM or so, and it would probably be just one segment. However, you may want to try either the MyHeritage cm tool or the segment/cm tool at dna-sci dot com and enter what info you have.

TD

[Biggles50]

In my Wife’s tree there is one full 4C at 37cM

A couple of full 5C in the mid 20cM range.

You could be looking at about a 4-5xGGP as the MRCA

[Cell]

Hi,
 I don't  have any (known to me  and 100% proven ) 4th half cousin matches. But  I do have a  few  known  and fully proven  4th full  cousins .
My very highest  4th full cousin is 92cm ( and his uncle who is my known 3rd cousin once removed is 128cm to me, which is a 3% possibility according to dna painter ) .

92cm  falls within the upper ends  of what 4th full cousins can share with these calculators ( 8% chance of him being my fourth cousin according  to dna painter - and  a measly 1% chance if you went by ancestry's  stats when you click on their relationships cm guestimates lol)

My child  doesn't  even share a match with my 4th cousin  on ancestry ( you'd think he would  wouldn't you ,  as me being  92 to him ) . My 4th cousins  uncle ( the 128cm one to me  ,  my 3rd cousin once removed ) is only on my heritage  , and he shares  with my son 42cm.
 My fourth cousin  is on both ancestry and Myheritage ( his uncle 128cm one, is only  on myheritage) and shares the same  cms with me on both sites - 92cm . He's a match  to my son on my hertiage by only 18cm ( where ancestry  hasn't  picked it up in his results at all,  or he is within the cut off under 8cms and isnt shown in his matches at all because of it.)

The rest of my know and proven 4th full cousins  are very low, in the region of 11cm  and upwards 20 something , 30 something.

So given  my highest known  4th full cousin of 92cm , your half cousin  may be 46cm  or more , in the higher end  region .
Or given  say one of my  lowest known full 4th cousins , the 11cm one, you could be 5cm with your  half 4th , or not even a match at all , even  though you are 100%  related.

It's extremely hard to say what you may , or may not share with your 4th half cousin,  or even a full  4th cousin . For example my 1st  full cousin only shares  with our  4th full cousin 13 cm , a little  less than my son  shares with him (on my heritage ) , yet I share 92cm (on both sites.) We are 100% not double related .
Use dna a painter for an estimate , but as a  rough guide only.
Many people , like myself do fall into  their lower percentages with some of our   100% proven cousins
https://dnapainter.com/tools/sharedcmv4
Kind regards

[LizzieL]

Use dna a painter for an estimate , but as a  rough guide only.
Many people , like myself do fall into  their lower percentages with some of our   100% proven cousins
https://dnapainter.com/tools/sharedcmv4

Thank you everyone.
DNA painter is always the first site I go to, but they do not list the half 4th cousin relationship, hence my question. I have tried to extrapolate from what they quote for half 3C and full 4C, but am calculating such a wide range.
I have an unknown 3 x great grandfather and cannot definitely find out what happened to my 3 x great grandmother after giving birth to my 2 x great grandmother. No obvious burial in her maiden name, so I suspect she married somewhere away from her home village. If either of the couple married someone else and had living descendants of the same generation as me, they would be my half 4th cousins. I have found a woman of the right name and birth year (calculated from age at death) marrying a man from a village 5 miles away. Although they had two children, both died young and then she died, so no living descendants. This with fit with not finding any shared matches with other descendants of my 2 x great grandmother. But I have a cluster of 5 people who only match within themselves and not to any known branch. They are a paternal match which is the correct side. They all share 21 or 22 cM with me, but I can't see how they're related to each other. Only one has a tree and it is too small to find any connection to my family, especially as I have no name for my 3 x gg-father. He might not even come from the same area as my 3 x gg-mother as she could well have been in service far from home. I was wondering whether the low 20s was likely for a half 4C.
Looking at a known 3 x gg-father, I have 5 half cousins descended from the son (William) of his first marriage
One H4C at 9cM
Three H4C1R at 12, 10 and 6 cM
One H4C2R at 11cM

These half cousins are descended from  3 of the children of William, and all are some degree of cousin to each other - none parent / child relationships.

Looking at my known matches in the low 20s, I am finding full 4Cs and 3C1Rs, even a full 6C at 21cM, but I know there is a cousin marriage in that line.

[Cell]

but they do not list the half 4th cousin relationship, hence my question. I have tried to extrapolate from what they quote for half 3C and full 4C, but am calculating such a wide range.

I've  never noticed that before, yes you are right, they seem to stop at  half 3rd cousin . I've  just put in figures from 6cm up to 50cm, and they don't  list half 4th at all.

I'd go by the same 4th full  cousin stats on dna painter for a   rough guestimate of what a  half can  share  ( ie don't half it) . It  doesn't  matter if your 4th cousin is half , it's a huge  range  what full  4th cousins  and  half  4th cousins can share that far back .
If I were a half cousin to my  full 4th cousin 92cm, perhaps I would be  sharing 46cm , which is  a 23%  chance for a full 4th  cousin .
Then you have  my 1st  full cousin's cms  of 13cm to our  same 4th full  cousin .
13 cm there is a 15 % chance he is a full 4th cousin ( which he is). Then Halve it to
6.5 cm   it's  still the same  15% chance.

10, 20, 30, 40 cms  can  easily be  either half or a full 4th cousin.
 It's  probably why they have a cut off  with the half guestimates, (4th half and beyond ) in their calculators .


Kind regards