Willow Smith once caught her parents having sex.

The 17-year-old daughter of Hollywood stars Will Smith and Jada Pinkett Smith has admitted that her ''introduction to sex'' came when she suffered the horror of accidentally walking in on her parents whilst venturing out of her bedroom late at night.

Speaking during the latest episode of Jada's 'Red Table Talk' series, she told her mother: ''My introduction to sex was obviously walking in on you and Daddy.''

To which the 'Girls Trip' star replied: ''When the hell did you walk in on us?''

Willow then added: ''It was in Utah ... not Utah. Aspen. I was going downstairs to get some juice and I saw for a little moment and I ran away. I was like, 'Oh my God, this is so crazy. What did I just see?' The room, it was dark. You know what I'm saying? It was silhouetted.''

The teenager's confession comes as a series of revelations from the 'Whip Ma Hair' singer, who recently confessed to her mother that she had self harmed during the height of her fame in 2010, when she was just 10 years old.

She said on an earlier episode of the Facebook show: ''I would have to say I honestly feel like I lost my sanity at one point. It was after that whole 'Whip My Hair' thing, and I had just stopped doing singing lessons and I was kind of just in this gray area of 'Who am I? Do I have a purpose? Is there anything I can do besides this?'

''After the tour and the promotion and all of that ... they wanted me to finish my album. And I was like, 'I'm not gonna do that.' After all of that kind of settled down, and it was, like, a lull, I was listening to a lot of dark music and it was just so crazy, and I was just plunged into this black hole and I was, like, cutting myself and doing crazy things... I honestly felt like I was experiencing so much emotional pain but my physical circumstances weren't reflecting that.''

Willow's mother Jada was shocked by her daughter's revelation and admitted she had ''no idea'' what was going on because she ''never saw any signs of it.''

But the young actress didn't even tell her older brothers, Jaden and Trey, what she was battling with and no one has realised because she's only got a ''little'' scar.

She explained: ''I mean, you can't even see it. There's still a little something there. Totally lost my sanity for a moment there. I never talk about it because it was such a short, weird point in my life, but you have to pull yourself out of it. One night I was like, this is actually psychotic, and after that I just stopped. It's been, like, five years.''