You don't have to have problems of the Junior Seau level to be affected profoundly. One of the most common effects of sports-related head injuries (doesn't even have to rate as a concussion) are learning disabilities. In the general population, the incidence of learning disabilities is estimated to be between 5% and 10%. At the colleges I've studied, among regular participants in the big three head injury sports (i.e., lacrosse, soccer, and football), the incidence is close to 50%! In most other sports (e.g., swimming, golf, tennis, gymnastics), the incidence closely mirrors that of the general population.

Granted, learning disabilities are not life-threatening, but they can be life-altering. People with learning disabilities tend to have significantly lower levels of educational attainment and economic success. The consequences of acquired learning disabilities tend to be more severe than those that are hereditary. Any father who wouldn't be concerned about such potential hazards is, in my opinion, a pretty crappy father.