I was interested in truest genetics for BS a few years ago and read up a lot on this via old forum posts, though I don't have much insight as a grower since I have a bit of a black thumb and usually how my plants grow is mostly just about how badly I mistreated them rather than genetics. If you want to know the early history of the strain this thread is invaluable, seems this is actually where the pepper was dubbed "Brain Strain" for the first time and theres some discussion and photos of some of the ppl who got seeds directly from Cappy early on:
I can't wait to get some yellow 7s growing off your plants AJ. :) I'm excited about that one (and 50 others..lol). Chris
thehotpepper.com
Regarding Duffy's acquisition of Brain Strain seeds in 2011 or so - seems he was never really convinced BS was even a different from Moruga Scorpion and his source doesn't seem to be direct from Cappy, so its possible he never had a good seed stock to begin with (or possible he's right and it was never different at all
). see below
Cappy I only grew Brain Strain once and it was Ronnie who gave me seeds in 2011 and he only gave me about 30. Last year was the first time I grew them. A guy named John gave a few in 2010 and it grew out to be chocolate hab. I have never gotten any seeds from Candice. Only person who ever gave...
thehotpepper.com
Also should point out that according to Cappy at the time he was just sending everyone seeds from a single plant with the correct phenotype and it was not even believed to necessarily be stabilized.
https://thehotpepper.com/threads/7-pod-skin-porn.6330/post-200194 - so theres a decent chance the branching genetics you are looking for were never really stabilized for...
I recall a few years ago I was convinced Judy/PepperLover was a decent source of original BS genetics but cant recall how I landed at that conclusion, probably somewhere in the thread linked at the top - but i dont know if I really trust pepperlover as a seed source anymore, last few orders from them have had terrible germination, slow turnaround, etc - not like when Judy was still running it.
Generally speaking I always trust Semillas - but cant attest to his brain strains specifically
Sorry I cant help more than that - I'm sure someone more knowledgable will pipe up