KING KONG star Jack Black has revealed he grew up in a bizarre sex cult after his parents attempted to save their marriage by signing up.

The funnyman tells style magazine GQ that he experienced naturist Family Synergy gatherings when he was a child, where everyone was encouraged to bare all in front of each other.

Black maintains his home life was deeply affected by the cult sessions because his father and mother shared their bed with another woman.

He recalls, "My parents met this other woman who ended up coming and living with us. In the same bed. They were trying to make it work... It was a meltdown."

The actor admits the break-up of his parents' marriage was a difficult time because his jealous mother would beat up his father's girlfriend, who Black, himself, had a crush on.

He adds, "She ended up leaving because she knew that I was crazy for her and was not into the weird unhealthiness of it."