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Sorry for the confusion....I am so new to all of this!
I meant that the line does not go all the way. It only covers part of it on the right hand side. Hoping my screenshot will come through so you can see what I meant.
Great! This absolutely confirms you cannot have the same father.
How do you know? They could have different mothers.
They are 1st cousins, not half sisters, so they do not share either a mother or a father. If they were paternal half sisters (different mothers), they would match (as "half identical") along the full length of the X chromosome - so in that screenshot, the purple bit on the X would cover the whole length, not the first portion that it does. So the amount of shared X DNA proves they do not share a father.
Just from looking at the DNA, they could be maternal half sisters (different fathers), since maternal half sisters only share about 50% of the (half identical) X chromosome. But since they know their fathers are brothers, that's highly unlikely. If they had the same mother and their fathers were brothers, they'd be 3/4 siblings: https://en.wikipedia.org/wiki/Sibling#Three-quarter and I'm pretty sure that would result in being fully identical (not half) on at least some portions of the X chromosome, which does not appear to be the case here.
This is what it looks like when two full siblings test on GED Match. This is me and my younger brother (Same Mother, Same Father). All the green areas are the DNA overlap we share from both of our parents. Virtually on every chromosome.
They are 1st cousins, not half sisters, so they do not share either a mother or a father. If they were paternal half sisters (different mothers), they would match (as "half identical") along the full length of the X chromosome - so in that screenshot, the purple bit on the X would cover the whole length, not the first portion that it does. So the amount of shared X DNA proves they do not share a father.
Just from looking at the DNA, they could be maternal half sisters (different fathers), since maternal half sisters only share about 50% of the (half identical) X chromosome. But since they know their fathers are brothers, that's highly unlikely. If they had the same mother and their fathers were brothers, they'd be 3/4 siblings: https://en.wikipedia.org/wiki/Sibling#Three-quarter and I'm pretty sure that would result in being fully identical (not half) on at least some portions of the X chromosome, which does not appear to be the case here.
This is what it looks like when two full siblings test on GED Match. This is me and my younger brother (Same Mother, Same Father). All the green areas are the DNA overlap we share from both of our parents. Virtually on every chromosome.
Yep, that's what full siblings look like, but it's not really relevant to this case, since it was never a question of whether they were full siblings or not, and I think I read the OP's cousin isn't on Gedmatch for comparison anyway.
But I will point out that those green segments are showing full base pairs or segments that are fully identical. Only people who share a significant amount of DNA from both their paternal and maternal sides will have significant segments of those (tiny slivers are normal for anyone - but large chunks are significant). So essentially only full siblings, or like I saying, 3/4 siblings (such as sharing a mother and their fathers are brother), will see long lengths of those fully identical segments.
We also have different maternal Haplogroups so, if I'm not mistake, then that would rule out being maternal half sisters :-)
Yes, it does, good thinking.
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