Your paper evidence seems to be fairly conclusive that the two are half second cousins.
The discrepancy to me appears to be your summation of the GEDmatch matches. It shows two segments over 7 cM that total 15.6 cM. Those are the two matching segments a GEDmatch One to One would show since by default it doesn't show segments smaller than 7 cM.
You are ...
There is a reference table of expected matching versus relationship on the ISOGG site here. This table shows the expected value (average value) of matching for a relationship; for half first cousins, it is 6.25% (or 425 cM). For different instances of half first cousins, it will randomly vary up or down from this value due to the randomness of genetic ...
DNA Painter thinks that the probability of 1449 cM being a half-uncle/aunt relationship is only 5.5%. It's much more likely that he's her full uncle, meaning the following diagram accounts for all of the numbers you've given:
| | |
D E F---G
Here, D is you, E is your male DNA match, and H is your ...
From The Shared cM Project 3.0 tool v4 for 439 cM the possibility of such a match being a half first cousin (Half 1C) is far greater than it being a half uncle.
Nevertheless, the latter is also possible:
Relationship probabilities (based on stats from The DNA Geek)
83.17% Great-Great-Aunt / Uncle Half Great-Aunt / Uncle Half 1C 1C1R Half Great-...
OK, so am I understanding it correctly that you have the following set of relationships:
?1 --- A --- B
C --- D E --- ?2
where F is you, and G is your cousin?
The easiest explanation for a match of 1760 cM between F and G is if ?1 = B, that is, your dad (B) is actually your aunt's (E's) full sibling, ...
Your 702cM match falls in the 553 to 1225 range that you would expect for 1st cousins.
Your 419cM and 468cM matches fall below the 553 to 1225 range that you would expect for 1st cousins.
However, they fall well within the range to be expected for half 1st cousins which is 137 to 856.
To understand what is meant by half first cousins I recommend reviewing ...
You should follow the DNA evidence rather than family stories or circumstantial evidence. Lack of a DNA match between two people is considered excellent evidence that they cannot be 2nd cousins or any closer relationship. (1/2 first cousin is closer than 2nd cousin).
In the Shared Centimorgan project, genetic genealogist Blaine Bettinger collected over 25,...