Chris Knight knew how to smile for the camera as Peter Brady on The Brady Bunch, but the former child star now admits he was suffering from Attention Deficit Disorder throughout the show's entire five-year run (1969-74).

"My whole life was an act," the 42-year-old Knight confesses to ADDitude, a lifestyle magazine for people suffering from ADD (a syndrome of various learning and behavioral problems believed to affect an estimated 3 to 5 percent of the population). "I always felt odd."

Knight, who today has found his niche as a partner in computer accessories company Eskape Labs of Pleasanton, CA, says he knew nothing about acting when he landed the part of Peter in 1969. "They weren't looking for actors, they were looking for a boy who had straight teeth and who looked like he could be Robert Reed's son," he says. "It wasn't until after I got the part that they realized I didn't know how to act."

Knight hid his difficulty memorizing lines and worked hard to appear well-adjusted off camera, fooling even his parents into thinking that he was happy. Today, as he watches Brady Bunch reruns, he realizes that his TV persona wasn't all that different from himself.

"Peter definitely had [ADD]," he says. "Peter was the one who was always getting into trouble. He was the one who got caught lying. He got fired from the ice cream shop and from the bicycle shop."