I'm glad you got a reasoned answer, OP, that seems like it makes sense. I would need to write this all down and make a chart. Might be helpful to you to make a chart that would help you track it.

Anonymous wrote:I'm my own grandpa?

Or are you Uncle Grandpa?

Anonymous wrote:I'm my own grandpa?

I am guffawing at this. Will you be my friend?!

Anonymous wrote:

Anonymous wrote:Your husbands grandfather married his own niece? That is so disgusting. gross.

+1,000. How did he not go to jail?

Who the f*ck did you marry OP??

OMG. You realize that this sort of thing was common even in the U.S. 100 years ago, right?

Anonymous wrote:Your husbands grandfather married his own niece? That is so disgusting. gross.

+1,000. How did he not go to jail?

Who the f*ck did you marry OP??

Anonymous wrote:There are so many other, more critical, lateral issues to this whole scenario that I cannot even begin to process the purpose of OP’s superficial mathematical question about actual DNA. Least of your worries.

OP here...Why? DH is not a product of any incest and this happened a long time ago in a Middle Eastern country.

Anonymous wrote:My family has double cousins (e.i., Jones brothers married Smith sisters, so all the Jones-Smith kids are double cousins). Their DNA matches show them to be as close as siblings in the match (usually about 50%, but varies).

So here is my take on your DH's family: the niece and your husband's father are double cousins and could present in DNA as possibly as close a match as siblings (roughly 50% shared DNA). Your DH's father would present as a half-sibling/double-cousin-once-removed to the niece's child (about 25+% DNA shared with DH's father).

Your DH, who got an X from a totally different family, would still would only be expected to share with the half-uncle (~12%)/second cousin (3-5%) as much as a first cousin (7-13%, though possibly on the higher side of that range. So 10% is not out of the expected range.

OP here...thanks for the information. It makes more sense now.

I need a diagram to follow this.

There are so many other, more critical, lateral issues to this whole scenario that I cannot even begin to process the purpose of OP’s superficial mathematical question about actual DNA. Least of your worries.

My family has double cousins (e.i., Jones brothers married Smith sisters, so all the Jones-Smith kids are double cousins). Their DNA matches show them to be as close as siblings in the match (usually about 50%, but varies).

So here is my take on your DH's family: the niece and your husband's father are double cousins and could present in DNA as possibly as close a match as siblings (roughly 50% shared DNA). Your DH's father would present as a half-sibling/double-cousin-once-removed to the niece's child (about 25+% DNA shared with DH's father).

Your DH, who got an X from a totally different family, would still would only be expected to share with the half-uncle (~12%)/second cousin (3-5%) as much as a first cousin (7-13%, though possibly on the higher side of that range. So 10% is not out of the expected range.

I would pose this question to a genetic genealogy group, on Facebook or on the web.

I would think your dh would share more than 10% but I am not an expert. It's also possible that if his family members got around this much, they may have also had "non paternal events" with others outside the family.

Your husbands grandfather married his own niece? That is so disgusting. gross.

I'm my own grandpa?

Are they from the Middle East? My childhood best friend’s parents were double cousins. When he was in high school, his dad divorced his mom and married her sister. His half-siblings look like full siblings in DNA.

So my DH took a DNA test and found a close relative via the DNA database. However, I am not sure whether the amount of DNA they share makes sense given their complex relationship. This is much more a curiosity question. So DH and this relative share about 10% of their DNA. This relative is both a half-uncle and a second cousin, but it is more complex than that. Basically, after DH's grandfather had DH's father with his grandmother, he married his niece and had this close relative. However, it is even more complex than that. The niece he married is the daughter of DH's grandfather's brother and DH's grandmother's sister. So in essence, DH's father shares more DNA with this half-sibling than a half-sibling if his grandfather had married a stranger. I would think that DH would share more DNA with this close relative, but am I off in my calculations?