Every detail of its regime has been laid out in endless writings by the movement's American founder, David Berg, dubbed Moses David. The Family now has 9,000 members in 50 countries who follow his writings, known as the Mo Letters.
The cult first fell into disrepute in the Seventies when his pamphlets promoting the "Law of Love" were exposed as pornographic tracts. But in contrast to the sexual liberalism there was also strict discipline, spartan living conditions and regular beatings for children, according to former members.
Among those who recall the harshness of the regime is Kristina Jones, 19, who escaped from the movement when she was 12, and was awarded pounds 5,000 compensation for being sexually abused by members from the age of three. "We were constantly moved round the communes so we didn't form close bonds with anyone, and we couldn't question anything," Ms Jones said.
"I was abused emotionally and physically, often hit on the head with belts and knuckles for doing nothing at all, and sex was rife. We had no idea of what the world outside was like."
So what has changed to convince Lord Justice Ward, who ruled yesterday that a mother could raise her grandson within the cult against the wishes of his grandmother, that the Family is a safe and happy environment in which to raise a child.
The movement was already concerned about the state of its image by the late Eighties. The practice of "flirty fishing", or getting new members to pay female members for sex, was dropped, and in 1985 the cult says that it ruled anyone involved in sex with children would be thrown out.
In 1991 the concern was revealed when internal documents were leaked that instructed members to destroy any "explicit" videos or pictures in their possession.
The Family opened its doors to childcare experts this year who visited the commune where the boy lives, showed them the dormitories where the children slept, the classes where they were taught, and the new guidelines, aimed at rewriting the wrongs of the past.
"A lot of people believe the Mo Letters are rife with sex, but that's only a small portion of them," Rachel Scott, a spokeswoman for the Family, said.
"We're only renouncing those parts that led people to believe interaction with minors was okay. That was wrong and should never have been written, but we are delighted that the judge has recognised that we offer our children happy and safe homes."Reuse content