Sara Gilbert is the sister of both Melissa Gilbert, who played Laura Ingalls, and Jonathan Gilbert, who played Willie Oleson on Little House on the Prairie. So it is natural to assume that Sara also had a role on Little House, especially as she was also an actress. Sara is best known for her role as Darlene Conner on the series Roseanne, as well as a recurring role on the Big Bang Theory.
Sara did not have a role on the show with her siblings, as she was significantly younger than both Melissa and Willie who were on the hit show, and the television series ended before she was of an age to have a guest role on the show.