For most of us, family means parents, grandparents, brothers, sisters and cousins. But for one film-maker, family, for many years, meant a sinister cult.
Now Paul-Julien Robert has turned his harrowing experiences into a film, My Fathers, My Mother And Me, which tells the story of the 12 years he spent in the Friedrichshof commune near Vienna.
The community he grew up in outwardly espoused free love and communal living. But these hippy ideals hid a very dark truth: in 1991, its leader, Otto Mühl was convicted of child abuse.
To make the film, Paul-Julien was able to mine the vast videotape library that the commune had amassed to document life there - many of its members believed they were conducting a grand social experiment, and wanted to record it for posterity.
Paul-Julien's documentary combines present-day interviews with the children he grew up with, as well as ex-cult members - including his mother - with fascinating footage from the Seventies and Eighties.
This includes clips of a group of naked adults rolling on the floor groping each other, interspersed with their blood-curdling primal screams.
The film, which won the Grierson award at this year's BFI London Film Festival, doesn't make easy viewing.
Robert didn't even know the name of his father until he left the cult, and describes himself as emotionally traumatised as a result.
Other damaging aspects of life in the cult included the demonisation of the family and the separation of mothers and children, in order to 'break down' the concept of the 'bourgeois' familial unit.
'Everything in the outside world was described to us as evil,' revealed Robert in an interview with the Guardian.
'I knew what a nuclear family was, but it was something distant and seen as destructive.'
Although he was allowed to remain with his mother, a Swiss woman named Florence Desurmont, for the first four years of his life, in 1983, when Robert was just four years old, she was sent to Zurich to earn money by the controlling and cruel cult leader, artist Otto Mühl.
'My mum was the only person with whom I felt safe,' remembers Robert. 'I had a feeling that she was something more and so she meant more to me.'
When she left, it was devastating. 'I was very lonely,' he told the paper. 'Other women replaced her, but they were never close to me.
'The ideology was that all relationships were bad for the group, so it was never possible to truly bond with someone.'
Tragically, he still feels the impact of her loss today and admits that he has struggled to overcome the experience.
'I grew up believing love was something bad,' he explains. 'The feeling of being loved, and of expressing love, was something I really had to learn and to accept later.'
He was able to begin to do so in 1991, when Mühl was arrested and imprisoned for sexually abusing minors and the commune shut down.
He was sent to Zurich to live with his mother, eventually building a relationship with her.
Now 35, he's about to become a father himself and although he admits to being occasionally nonplussed by his girlfriend's emotional approach, expects to take parenthood in his stride.
But although he's no longer the emotionally traumatised boy he once was, he says the harrowing experience of growing up in a commune still haunts him.
'For me, a nuclear family is like a small commune in a way,' he explains. 'Each individual has their own opinion and to find a way to be together without losing one's self is very difficult.'
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