Genetic distance in cousins and brothers

[Jeannie Felts]

My husband, his half brother (same father) and his cousin (father's brother's child) had their Y-DNA tested. My husband tested exact match in 37 out of 37 markers with his cousin but is -1 genetic distance from his half brother at the 25 marker level (the final 12 markers aren't in). The one difference is the 25th marker - Dys#464d. Does this mean that my husband and his half-brother do not have the same father - a real surprise since they look remarkably alike? By the way, my husband and his brother and cousin are in their 60s - all parents are deceased. I am told that this is a negative test - can only prove conclusively that someone is not related but cannot prove a relationship without futher testing. We are all very curious about this and would like feedback. Thanks!

[GvdM]

No, a mutation just took place at birth is all. You cannot tell paternity from ydna testing. My grandfather and my cousins father were brothers and differed by a GD of 1. Also 464d is a relatively fast moving marker.

[ntxcousin]

Something similiar just occurred with my DNA tests. I found a 24/25 match with a one step mutation at DYS458. That person has the same surname as me and has documentation going back to the same ancestor.

It would be interesting to get him to do a 67 marker upgrade so we can completely compare results.

[GvdM]

Something similiar just occurred with my DNA tests. I found a 24/25 match with a one step mutation at DYS458. That person has the same surname as me and has documentation going back to the same ancestor.

It would be interesting to get him to do a 67 marker upgrade so we can completely compare results.

How many generations to the branch since you have paperwork? Again, 458 is a fast moving marker. With the paper documantation this is the perfect synario to run out to 67-markers.

[ntxcousin]

How many generations to the branch since you have paperwork? Again, 458 is a fast moving marker. With the paper documantation this is the perfect synario to run out to 67-markers.

There's 300+ years to the common ancestor.

[GvdM]

There's 300+ years to the common ancestor.

So roughly 20 or so generations round trip and ony one mutation at 25 markers. That is a confidence booster in DNA testing for sure.

[citroen25]

My first cousin ( my father s brother son ) and I have at 37 markers ydna test genetic distance 1 , does this confirms that he is my first cousin , my oncle son or not

[Jim Barrett]

A genetic distance of 1 on 37 markers could be as close as father/son or brothers. It could be as distant as beyond a genealogical time frame. Autosomal DNA will give you a much better idea of the relationship.