Reality TV star Jack Osbourne was so out of control as a teenager, he once attacked his sister KELLY with a knife. The 21-year-old son of rocker Ozzy Osbourne admits he found it impossible to control his temper with his family and was forced to take anti-depressants to control his behaviour. He says, "From the moment I became a teenager I started having trouble controlling my temper. "I would have these incredible fits of rage, I'd trash my room and get into really nasty vicious fist fights with my sisters. I think the boiling point for my parents came when I held a knife to Kelly's throat."