Tori Spelling finally knows exactly why her character on "Beverly Hills, 90210" stayed a virgin for all those years. Spelling played Donna Martin on the hit show and learned it was her late father, Aaron Spelling, who suggested she abstain from sex. "I remember very clearly when he said to me…Donna should be a virgin," "90210" producer and writer Charles Rosin revealed on the latest episode of Spelling's "9021OMG" podcast.