Hi OH,
good questions.
Firstly, the "confirmed" status on FTDNA just indicates whether the individual has tested, and had confirmed, the specific SNP mutations that define the haplogroup.
Looking at the Goforth group results shows that the individual with the "confirmed" J-M172 haplogroup has only tested to 11 STRs (which is nowhere near enough to confirm) - so must have separately bought a SNP pack to confirm. The SNP pack is not as good as a Big Y - so has confirmed a haplogroup that is very old (much further up the tree at 25,000 BCE according to this page).
From this page you can see that J-FT201943 (about 1700CE) is derived from J-FT200913 (about 1150CE), and they are both derived from J-M172.
You will note that all of those ages are older than the given common ancestor, so that could indicate three things:
- The age estimate is wrong,
- The required mutations have happened more than once
- There are not enough testers to name derivative haplogroups
To answer your questions:
- Each birth has the potential for mutation in both STRs and SNPs (I have STR differences to my father, for instance). These happen more slowly in SNPs than in STRs. The SNPs are what defines haplogroups. So, I would suggest the J-M172 result is just that they haven't tested enough SNPs to refine it further, and the J-FT201943/FT200913 results are because someone along the line picked up a few extra mutations and passed them down their specific line.
- George is almost certainly lower down the tree than J-M172 - that haplogroup is so old that mutations must have occurred. He would be a parent branch of the modern groups, most likely, as SNP mutations occur roughly about once or twice per century (as I understand it).
