Donor Unknown is a documentary feature following the journey of JoEllen Marsh as she goes in search of the sperm donor father she only knows as Donor 150. JoEllen, now 20, has always known her family 'wasn't like other families'. She grew up in Pennsylvania with two mothers, and a burning curiosity to know more about her anonymous donor father. When she discovers a unique online registry which connects donor-conceived children, she manages to track down a half-sister in New York. The New York Times picks up the story, and, over time 12 more half-siblings emerge across pigeon in a broken-down RV in a Venice Beach car park. In the 1980, Jeffrey supplemented his meager income by becoming a sperm donor at California Cryobank. His number was Donor 150.