Big Y Matches

 

Source: FTDNA. 14 Feb 2026.

The match time tree for cousin Greg's Big Y results shows two matches in the same haplogroup, with a most recent common ancestor born about 1234 CE. The time predictor tool on one match shows a range of 950-1650 CE, likely about 1350. There are also a few Y-37 matches that show a most recent common ancestor at about 1500 to 1550.

I provided a prompt to Claude that we have a Big Y match with STR differences 3 of 590, and what tools could I use to understand if this was an actionable match. The response was "A STR difference of 3 of 590 is actually quite close and could definitely be worth exploring. Here are several tools and approaches you can use to determine if this is an actionable match." I've already looked into the suggestions for using FTDNA's tools on the Block Tree, Match Time Tree and Time Predictor, so I'll skip down to Claude's suggestions on why this could be an actionable match.

"With a 3 of 590 STR difference, this suggests a recent shared ancestor, likely within the past few hundred to perhaps 1,000 years." This is consistent with FTDNA's statistics in the time predictor, and in the image above.

Next, Claude says "check for shared SNPs - do you share any terminal SNPs beyond your haplogroup assignment". This is good and gives me something to check.

"Compare family trees - look for surname matches, geographic overlaps, or common ancestral locations." So far, the surnames do not overlap, but from a geographic location we're dealing with northern Mexico and Spain as common locations.

"Review genetic distance - FTDNA should show a genetic distance value that helps estimate generations to a common ancestor." Also a good suggestion.

Claude recommends the following next steps:

1. Contact the match 
2. Check geographic origins - do the paternal lines come from similar regions? (I'd like to see a bit more information on common regions in Spain).
3. Look at surnames - any surname matches in my own ancestry? (Not yet).
4. Consider STR marker patterns - which specific markers differ? Some mutate faster than others.

I am rewatching the YDNA course on YourDNAGuide, and need to review the modules on STR markers.