Grace from Little House on the Prairie was played by a twin, named Wendi and Brenda Turnbaugh.
Melissa Gilbert, who played Laura Ingalls in Little House on the Prairie, and Jonathan Gilbert, who played Willie Oleson in Little House on the Prairie, are brother and sister.
Carrie Ingalls from Little House on the Prairie was also played by a twin, Lindsay and Sidney Greenbush. The opening credits of the series showed one of the twins running in a meadow behind the name: ''Lindsay Sidney Greenbush''. All the people who watched the show thought that was the full name of the little actress who played Carrie, but it wasn't.
Haylie Duff, who played Dr. Annie Nelson in the Love Comes Softly series is the older sister of Haylie Duff, who played among other in Cheaper by the Dozen as Lorraine Baker and in the Perfect Man as Holly Hamilton. Hilary and Haylie acted together in several movies.
Elizabeth McGovern, who played Lady Cora Crawley in Downton Abbbey and Michelle Dockery, who played Lady Mary Crawley in Downton Abbey, are singer-songwriter(Elizabeth McGovern) and occasionally singer(Michelle Dockery) of Sadie and the Hotheads.