Jessica Biel won't be around DRUGS.

The 30-year-old actress - who is engaged to Justin Timberlake - leaves parties if people's behavior seems to be getting too wild or out of control.

She said: ''If there is a huge drug fest happening and everyone is getting it on In The Bedroom, it is probably time to leave.''

Jessica's sensible attitude stems from her teenage years where, even though she was a working actress, she still had to live by her family's rules.

She explained in an interview with The Sun newspaper: ''I was lucky to get a part in a long-running TV series, '7th Heaven', when I was 14, and everything took off from there.

''It was like having two families, my real one and the cast.

''My mom had me under curfew, so I was well known on TV at the same time as having to be back home early.''

Jessica also credits her mother Kimberly with giving her a sensible attitude to her body image.

She said: ''My mom Kim taught me an important lesson in Hollywood - if someone says you are too fat, tell them to p**s off.

''My mom brought me up with sports and a healthy image. It was just how we lived.

''With her attitude and upbringing, I have been lucky not to have an eating disorder or a drug habit to stay skinny.

''I am 5ft 7in and don't go along with the Hollywood obsession with weight.''