Encouraging kids to join athletic teams once seemed like a forgone conclusion. But following former Patriots linebacker Junior Seau’s suicide and the NFL’s $100 million grant to Harvard and its affiliated hospitals to study repeated brain trauma and other chronic injuries in former NFL players, many parents are now raising concerns over the risks for young athletes. Michael O’Brien, HMS clinical instructor in orthopedic surgery at Boston Children’s Hospital and Richard Ginsburg, HMS assistant clinical professor of psychology in the Department of Psychiatry at Massachusetts General Hospital, are quoted.