The Complexities of YDNA Haplogroups/Why even close relatives can be assigned different terminal SNPs

In addition to providing information about our ancient origins and migration patterns, haplogroups can also be a valuable tool in genetic genealogy. Haplogroups can help us identify possible relatives who share a common ancestor on our patrilineal or matrilineal line, even if they don't share enough autosomal DNA (atDNA) to be detected as a match.

As an example, consider the case of two Browning male cousins who matched my mother with different terminal haplogroups at 23andMe. Despite not matching each other based on their atDNA results, they are likely distant cousins who share the same YDNA haplogroup, but not terminal haplogroup. This means that they both inherited their Y-chromosome DNA from a common ancestor on their patrilineal line, even though they have different terminal SNPS. 

This information is particularly useful for our family because we are looking for  Browning males to test in the Browning line for a YDNA project at Family Tree DNA. By identifying individuals who share the same haplogroup, we can narrow down our search for potential relatives who are more likely to share a common ancestor on our Browning patrilineal line. Since AncestryDNA doesn't provide YDNA haplogroups it can be tricky selecting a male to test because there could be a break in their direct male line. 23andMe does provide that useful information. If two men are in completely different haplogroups we know there is a line break. 

Haplogroups can vary even between parents and their children, according to a 23andMe post. A child might be assigned a different haplogroup than their parent due to missing data or other factors. This means that even if two individuals share a common ancestor on their patrilineal or matrilineal line, they might not have the same terminal haplogroup SNPs. However, they are still likely related and share a common ancestor on their direct paternal or maternal line.

To be safe we will try to find at least two men to test for our Browning line to ensure there are no line breaks. There is a Browning male who already tested at Family Tree DNA. They took the 37 marker test, which basically only put them in the R haplogroup. I believe a good marker match would be enough to prove a relationship to him. Since all the Browning males, so far, are in the R haplogroup it seems to be a good sign they are likely all related, although they are in a very common haplogroup for Europe.  

Haplogroups are a powerful tool in genetic genealogy that can help us identify potential relatives who share a common ancestor on our patrilineal or matrilineal line. By understanding the implications of haplogroup differences and similarities, we can make more informed decisions about our DNA testing strategies and better understand our family history, even though SNP assignments can be confusing.