100% of footall players autopsied for this (actually more like 80% now). Which is an expensive and long process requiring donation of brain to the study, something you do onlynif you suspect CTE. It is a very misleading and self selected sample. We only know that a lot of football players have had it. We don't Know how common it is in general public or how common it is among all former football players and what factors contribute to it (genetic predisposition, other trauma are cretin people likely to get it regardless of sport played etc. Current data is alarming and something that needs to be studies a lot more but for you to be 99% certain abut anything is silly.
This may be what is being referred to.
http://www.cnn.com/2017/07/25/health/cte-nfl-players-brains-study/index.html
IMO it's not misleading. The fact is, of those studied, it's by far the majority. As for "all former football players", it's impossible to know until they are all dead and tested. That's not a fair argument in this context.
CTE has been proven to be a result of head trauma. Football has been proven to cause head trauma. Unless you can point me to some study that states otherwise, I've yet to read anyone comment on genetic predisposition relative to CTE.
I'm not trying to start an argument with you on this but if in fact it wasn't as fairly obvious as it is, after all the research, the billion dollar animal that is the NFL would be working a LOT harder to dispell any of it than it is. They aren't, because they can't.
At the end of the day, it would be better for people to simply admit they know there is greater risk than initially thought and live with the consequences. That said, do you allow kids to make that decision...or allow parents to make that decision? Rhetorical questions, maybe.
In the end, I do love the game and played it for years. Would I let my son? Right now, it would be very difficult for me to be ok with it.
In any case, I think it's a stretch to assume that anthing JK has done is related to CTE and it's unfair.