Alan Thicke had quite the career in front of the camera, most recently popping up on This Is Us and Fuller House, but the beloved sitcom dad also had a hand in things behind the camera, namely writing some of TV's most beloved theme songs. In the 1980s, Thicke, who passed away from a heart attack at 69 on Tuesday, Dec. 13, helped create a number of iconic TV theme songs, most notably the opening numbers for The Facts of Life and Diff'rent Strokes. "It Takes Diff'rent Strokes," the theme song for Diff'rent Strokes, the 1980s comedy starring Gary Coleman, Dana Plato, Todd Bridges and Conrad Bain was composed by Thicke, his then-wife Gloria Loring and Al Burton. Thicke sang on the opening...