So are you denying a link between repeated concussions and depression, dementia, and suicide?
Just take a good, long look at the history of boxing.
Or is your position, much like the NFL's will undoubtedly be, that these young men understood the risks they were taking?
How can you understand the risks you are taking without knowing if you are genetically predisposed?
Or are you refuting the link to genetic predisposition?
Tons of studies, linkage like the one below--
"As brothers, Eric and Brett Lindros realized the boyhood dream of almost every red-blooded Canadian male – playing professional hockey for a living in the National Hockey League.
But as they came to discover, their sibling bond extended beyond a shared affinity for big goals and even bigger bodychecks, the dream souring as multiple concussions deprived both of prolonged careers. Brett, the younger of the pair, was the first to go in 1996, forced to hang up his skates after just 51 NHL games having suffered three concussions in a little over a year. At that time Eric had yet to suffer his first, but once he did, in 1998, they came thick and fast, with seven more to follow over the next six seasons before he finally called it a day in 2007."