Parent HaplogroupI-Y32666 (I-BY21365)
WebIntroOct 2021: yFull still shows both I-BY21365 and I-BY21376 as equivalent to I-Y32666 in their v9.04.00 tree as it appears those splitting these branches are not on yFull. So no time estimates are available from yFull for this split.
FTDNA shows this I-BY21376 branch as containing15 SNP generations.
Depending on how many years you allocate per SNP, at say 75 or 100 years this is about 1125 or 1500 AD

There are now two sub branches (and on FTDNA another tester awaiting a match to further refine his sub branch):
I-BY34592 - the Elliiott surname outliers who match Faibairns, and
I-BY21384 where the majority of the Scottish Borders Fairbairn families are sub grouping nicely.
(yFull currently shows the 3 sub groups of this at the same level as the Elliott's group - hopefully our new kit may help thiis along for revised time estimates)

Dec 2018 saw I-BY21376 split out as a sub branch of I-Y32666/I-BY21365 on the FTDNA tree, and all the BigY tested Fairbairns and matching Elliotts to date shfted to underneath this branch, as opposed to the now higher branch I-BY21365/I-Y32666.
WebLink(YFull) I-BY21376 on FTDNA
ChartsHaplogroup I
Last Edited16 Oct 2021

Sub haplogroups/tested lineages/testees