A New Terminal YDNA Subclade for My Wife’s Butler Family

I have been testing my late father-in-law’s YDNA since 2015, so this has been a long journey. Recently my brother-in-law also had his YDNA tested. He went all out and got the BigY-700 test. This was good because once two people who are closely related both have this test done, then it defines the terminal subclade for that specific family.

So, What is the New Subclade?

The new Subclade is:

Here is how it looks in FTDNA’s Block Tree:

Previously my father-in-law, Richard was I-128364. The odd part about this is that the figure still shows 8 Private Variants between Richard and his son. I don’t see any private variants for Richard. That must mean that his son has about 16 private variants as this is an average of the two. My guess is that FTDNA has not updated the Private Variants yet.

SNP Tracker

The SNP Tracker has not yet tracked I-FT241245. However, this is what it now shows for I-Y128364:

This tracks the migration that the Butler family took since the dawn of time. Note that the Roman period is skipped over and this just brings us up to Medieval times. The Roman period must be bound up in the block of 23 SNPs that are listed here under I-Y128591:

I-FT241245 Is Not the Terminal SNP I Was Expecting

David Vance from the Big Y Facebook Page points out that:

By the way this also says that the father and son both share two variants that are unique to their line, FT241245 and Y129564. Those are two separate SNPs that apparently occurred on the father’s line after his most recent common ancestor with the Butler in England. FT241245 is at position 4195963 and Y129564 is at position 20968182.

This surprised me a bit as previously, I thought that Richard would have one SNP. This is based on the fact that Richard previously had one private variant. My guess is that either the manual review is not finished yet, or Richard’s son had a SNP at position 4195963 resulting in and that Richard had that also, though perhaps they weren’t sure before that Richard had it

I have found that YDNA can be full of surprises.


I looked at Richard’s CSV file and found this:

This shows that Richard already tested for this SNP but that there was a question. this is shown as a known SNP because this is a new CSV file. I assume that the original file only showed this as a position number.

The FTDNA Y Chromosome Browsing Tool shows this for Richard:

Richard had only two reads for this SNP and several more reads are needed before they are accepted.

This was accepted based on his son being positive for this SNP:

The other question I can’t answer is why they chose this SNP to name the branch and not Y129564.  I might have chosen Y129564 due to the testing problems for Richard of FT241245.


Here is how Richard tested for Y129564:


Why Do Richard and His Son Have Two Terminal Subclades?

Here is the tree I had before Richard’s son tested:

I-Y128364 appears to represent the Wexford Butlers. At least that is the opinion of the Butler researcher from England. That makes sense because my wife’s ancestor, though he was probably born in Kilkenny, was born near the Wexford border. The George Butler family from Cincinnati who my wife’s family is related to by autosomal DNA was originally from Wexford. Also the English researcher’s family was from Wexford.

Above, the 225 years before present date is important. Here is the new tree:

The English Butler and the American Butlers shared a common ancestor around 225 years ago. This date could be earlier based on known research. However, since that time, the American branch of Butlers has had 225 years or so for new SNPs to form. New SNPs form at about the rate of every 83 to 144 years depending on the coverage of the BigY test taken. So in those 225 years or more, there was time for two SNPs to develop in the American Butler Line. Unfortunately, without further testing, we don’t know which SNP formed first.

This would be a good place to look for additional BigY testers:

Richard had a Great Uncle George born about 1873. This George had 8 sons. We just need to find a surviving male Butler from that line to test. This descendant of George Butler would probably be either I-FT241245, Y129564 or less likely neither. If he was neither, that would mean that the two new SNPs happened only on the line of George’s brother Edward Henry Butler born 1875.

Private Variants

Here is the Block Tree again:


Richard’s Private Variants do not show. However, he presently has 0 private variants. Before Richard’s son tested, Richard had one private variant. However, we now know that he should have had 2 private variants. One of those private variants had ambiguous results. Those 2 private variants formed I-FT241245 and Y129564.

Richard’s Son

I can only assume that Richard’s son has about 16 Private Variants as Richard has 0 and the average private variants between the two is 8. I have asked Richard’s son for his private variants. I assume that these may be bad readings or false readings or matches with Batt or the England Butler or new SNPs from up the tree. The other issue is that Richard’s son has taken the BigY 700 which has more coverage than the other BigY testers. That means that Richard’s son may have new SNPs that were not previously discovered.

Butler (England)

This Butler has two private variants which is consistent with Richard’s two New SNPs. If this tester finds a close relative to test the BigY, he will likely have his branch named with two new SNPs. If he finds a more distant relative, he may define one out of two of his now private variants.


Batt has 5 private variants. He shows his ancestry going back to Joseph Whitson in England in 1615. If we say that the SNPs were formed every 144 years for this older BigY test, that gets us back 720 years. That is roughly the year 1300, so quite a while ago. That suggests that the common ancestor between Butler and Whitson was in England at this time. Perhaps one line stayed in England and became Whitson, while another line went to Ireland and became Butler.

Next Steps

  • FTDNA is likely looking at Ken’s private variants. These should get down to one or zero for Ken.
  • We will want to check the SNP Tracker to see if it picks up the new SNPs for Richard’s line. I don’t know if they wait until FTDNA’s manual review is over or not.
  • It would be nice to have additional BigY testers.



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