10 Celebrity Couples Who Fell in Love After Playing Onscreen Siblings

Jason Behr and Katherine Heigl starred as orphaned extraterrestrial siblings masquerading as normal high school students Max and Isabel Evans in the sci-fi series Roswell in the late '90s. Katherine and Jason briefly dated throughout filming, but the show was canceled in 2002.

It's safe to say that Maggie Grace and Ian Somerhalder's characters on Lost have a complicated relationship as stepsiblings Boone and Shannon, who end up in bed with each other. After Shannon and Boone were both written off the show in 2006, their real-life counterparts dated for about a year and remain close friends.

Although Matthew Broderick and Jennifer Grey play warring siblings in the '80s classic Ferris Bueller's Day Off, the two of them clearly hit it off on set. Their romance fell apart, however, after they were involved in a fatal, head-on car crash while on vacation in Ireland in 1987, which claimed the life of the mother and daughter driving in the other vehicle.

The Wizards of Waverly Place costars might have been brother and sister on screen, but they fueled romance rumors by stepping out together during one of Selena Gomez's "off" periods with then-boyfriend Justin Bieber.

Since The Brady Bunch is known for its wholesome family values, it might come as a surprise that there were a bunch of romances going down behind the scenes. After Barry Williams revealed that he took his 36-year-old onscreen mom, Florence Henderson, on a date when he was 15 in his book Growing Up Brady, it also came out that the actor later linked up with his "sister" Maureen McCormick. Maureen, who played Marcia, detailed her fling with Barry in her own book, Here's the Story, saying that they engaged in passionate makeouts on the beach while filming in Hawaii, and she'd planned on losing her virginity to him. Talk about keeping it all in the family, huh?

Following Everwood's cancellation and the end of her relationship with Chris Pratt, Emily signed on to play Rebecca in Brothers & Sisters in 2007. If the title of the show is any indication, Rebecca was the presumed sister of Justin, played by Dave Annable. In an interesting turn of events, Emily and Dave supposedly had so much chemistry off screen as IRL boyfriend and girlfriend that the writers of the show cooked up a paternity scandal that made Rebecca and Justin unrelated, so they could have them start dating and eventually get married on the show. However, just like their characters' doomed relationship, Dave and Emily later broke up, and he married actress Odette Annable in 2010.

Although Peter Krause and Lauren Graham had known each other for years before they started dating in 2010, the couple got close when they starred as Adam and Sarah Braverman in NBC's much-loved family drama Parenthood. Their relationship is still going strong, which Peter told ABC is due to them "[keeping] things pretty private." So cute!

During Shannen Doherty's tenure on Beverly Hills, 90210, the actress was well known for causing drama on set, but she also made time to date her onscreen twin brother, Jason Priestley. In addition to being photographed making out on the red carpet at the Emmys in 1991, Jason commented on all of the behind-the-scenes hookups on 90210 while promoting his memoir, telling Access Hollywood that "nobody ever got attached. We never let it get in the way what we were doing. I will let you know that nobody ever got — work always superseded everything."