Gnarly Double Cousin DNA issue
| # | Post |
|---|---|
| 1 | We'll, it is gnarly for me. Girl 1 marries Boy 1 and then his sister Girl2 marries Boy 2, the brother of Girl 1. I know the the relationship between their children is treated as half siblings rather than first cousins. Each couple has a daughter - Girl 3 and Girl 4, and each has different mitochondrial DNA. Since they are clearly different people, could the two respective fathers be considered to be the same man, as with half sibling situations? Question arises because G3 and G4 each have daughters and they are showing as second cousins. That is OK, but what appears to be happening is that the separate family members are being attributed to the wrong cousin, eg the family of G4 is being attributed to that of Girl 3. Is that really happening? blackhalls - 2019-06-24 13:35:00 |
| 2 | Since the fathers are brothers-in-law and not brothers, they should not come out as brothers in DNA. But they could be related eg cousins which would complicate the DNA further. Are you saying that the matches for G4 are coming out as the family of G3 that she isn't related to? Or people are getting them confused in their trees? rednicnz - 2019-06-25 14:51:00 |
| 3 | There is a name for the children of two siblings marrying two siblings but I have forgotten it. Haven't heard it called half siblings though. Edited by gilligee at 7:49 pm, Tue 25 Jun gilligee - 2019-06-25 19:43:00 |
| 4 | Mitochondrial DNA, unlike "ordinary" DNA, is passed on only by females. You only inherit it from your mother, whether you are a boy or a girl. So unless Girl1 and Girl2 are sisters, their children and childen's children will not have the same mitochondrial DNA. downshire - 2019-06-25 23:27:00 |
| 5 | rednicnz wrote:
Girl 1 is sister to Boy 2. Girl 3 has a daughter Girl 5 who has tested for DNA Girl 5 has DNA matches, the closest being a second cousin. This second cousin, her father, and her grandfather all have the same surname as G4's paternal grandmother. I will have to give the grandmother a label - H. Researchers try to attach the matches to the father of G5, finding nothing to confirm this in an extensive family tree - so far! They have been led to suppose some family irregularity hides the link. This supposition is shaky because only his children appear to match the name H. The descendants of his siblings do not match the name H. One descendant of his half-aunt does have a match to H but we can find that connection in the family of G4 as well - namely G4's husband, his mother, and their extended family. Clearly G5 DOES have a type of connection, but not through her father. Without further information it has to be a connection through her half-sibling G4 who married H's son. The connection should NOT be there, hence my question about the possibility of the gene test not picking up on the double-cousin, half-sibling issue of this type if only one side of the equationn has tested. This is so convoluted it makes the head swim. Sorry about that. Edited by blackhalls at 11:37 pm, Tue 25 Jun blackhalls - 2019-06-25 23:36:00 |
| 6 | downshire wrote:
Yes, and G1 and G2 are not sisters. The G1/G3/G5 line is all female, and so is the G2/G4/G6 line. The Mitochondrial DNA from H is interrupted and cannot be passed on from H's son to G6. G5 and G6 are assessed as half first cousins. They have different mitochondrial DNA and different fathers. This is so hard for a lay person to explain. blackhalls - 2019-06-25 23:50:00 |
| 7 | Are we talking about mitochondrial DNA matches or autosomal (eg Ancestry) DNA matches? If you're talking autosomal, then the shared matches will show which side of the tree these matches are related on. If there are no matches on the father's side, then it will be on the mother's side. I'd ignore people trying to prove a link based on the last names! Unless it's an incredibly rare name, these things happen! (and names change every generation for mitochondrial DNA results!) If G5 and her match are both descended from Girls 1&2 and Boys 1&2, they will have 3/4 of the same DNA relative to the generation (give or take a bit). So first cousins (G3 and G4) will have 3/4 but another generation removed would have 3/8 because G5 and G6 will have half their fathers' DNA. Hope this is making sense. Have you tried the Shared cM tool? You will need to bear in mind the possible double cousins. But with it you can see the range of relationship which might help sort out where the match fits in. rednicnz - 2019-06-26 18:31:00 |
| 8 | I think that you are right. No connections have ben made except by the use of surnames and location, and it seems that only the male names have been considered! The researchers involved have accepted the family trees of the matches without question and seem have decided on an unknown aspect of G3's husband's family. I can't see how an unknown person can be used to prove an unknown connection! The second cousin match to G5 is 293 cMs. I don't have other details to hand. I think that, before decisions can be made to add this cousin to our tree, that much more research is required. I will write to the second-cousin 'match' to ask for more information. I have played around making star diagrams with the matches and intermatches, and discovered that they all make up a closed circle of names with about four 'centres'. It looks to me as if there are only about four family groups involved - at the moment. Any ideas welcome. blackhalls - 2019-06-26 21:33:00 |
