Jonathan is the adopted brother of Melissa Gilbert, who played Laura Ingalls Wilder on the show, and the brother of Sara Gilbert, who played Darlene on Roseanne. He is also one of only five actors on Little House on the Prairie to appear throughout the entire series. In 1979 he starred in a movie called the Miracle Worker where he played a boy called Jimmy. He worked for a few years in New York as a stockbroker and then traveled around the world, only rarely making news. He was involved in charitable projects in South America and Africa for a time. Then he returned to California, where he works for a theater company.