The family of former San Diego Chargers star Junior Seau, who killed himself last year, sued the National Football League on Wednesday, claiming that his suicide resulted from brain disease caused by repeated hits to the head during his football career. The wrongful death lawsuit, filed in San Diego Superior Court by Seau’s children and ex-wife, as well as the trustee of his estate, also claims that the NFL concealed the risks of brain damage in the sport, court documents showed.