The Awful Truth is episode 19 of Season 2 of Growing Pains.  


While working on a school project, Ben uncovers a startling secret: Jason was previously married. Armed with this shocking knowledge, Ben, Mike and Carol do some additional burrowing into the Seaver family catacombs to find out if they have any heretofore unacknowledged half-siblings lurking throughout the world. This leads them to expose still another shocker: Maggie was previously married before too.