Would the children growing up on camera play out or defy the statistics presented in the study? How much would their circumstances define their characters? How much would their characters define their experiences of life?

Those babies are now seven, the age at which, according to the Jesuits, the character of the adult is set. Carter-Mangan's daughter, Shine, who was born into a family running from substance and physical abuse, has grown up to be ''tenacious, intelligent, quick'' and wants to be a biomedical engineer - a portrait that mirrors the fortunes of her household.

But the past seven years have tossed her peers in every direction. The group was designed to represent families across the spectrum - young, old, indigenous, new and those with disabilities - and over the years it has come to symbolise something else. The latest instalment, Life at 7, reflects those to whom life has been kind and those to whom life has not been so kind.

''I think it really marks the progress that we've made and there's a lot of pride there,'' Carter-Mangan says. ''If you were to look at where we were at Life at 1 and where we are now, we've changed our lives.''

Jennifer Peedom is the series's third director, posing a potential challenge for a project that depends on the subjects' trust in the filmmaking team. But she credits the producer, Jennifer Cummins, in presenting her with a ''pretty seasoned'' bunch of participants.

''So much of that hard work is done,'' Peedom says. ''They know so much more what they're up for, they have respect for the series, they like being involved and it's a matter of building on that and not messing anything up, really.''

Peedom had been a keen follower of the series before she became involved and was already curious about the children's lives. But the Life series is unlike other documentaries that return to people's lives, such as the Seven Up! series, in that its raison d'etre is the Growing Up in Australia study to which it is linked. This draws a tension between writing a drama and a writing a science series. Peedom's answer was to follow the stories, and build the science around the narrative instead of the other way around.

''That's very much my instinct as a filmmaker,'' she says. ''I actually stopped referring back to the study and quoting statistics and I stopped doing a lot of that stuff because it wasn't helping tell the story.''

Each series concentrates on different aspects of the children's development through behavioural experiments in the ''life lab''. Peedom decided to start filming in the life lab and see if that threw up any leads for when she visited the children in their homes. The strategy paid off, never more so than in the case of Jara'na.

The Aboriginal boy was notoriously shy, but one experiment involved leaving the children in a room to see how they behaved in a group. Jara'na surprised everyone by taking a leadership role, offering insights into his personality and indicating he was much more natural in the absence of adults. ''Suddenly he was there calling the shots,'' Peedom says. ''I had expected him to be a lot more shy.''

So when the crew visited him at home, they fitted him up with a radio microphone and shot him through a long-range lens. ''He just forgot about us,'' she says. ''The sound recordist said, 'My god, I've never heard him talk so much.'''

Another experiment, which involved observing the children as they watched footage of a boy apparently grieving the loss of his mother, was similarly illuminating about Daniel. His reaction to the clip hinted at his own insecurities and it later transpired that he had witnessed an incident between his parents that left him traumatised.

Life has not been easy for Daniel. Coping with the loss of a brother, his parents' divorce and his mother's failing sight, he has publicly morphed from a sunny baby to a worried little boy. Yet his mother, Kath, remains committed to the project. ''Obviously, it's hard to put real emotional trauma out for all the world to see, but at the same time, it happened,'' she says. ''Drownings happen and brain injuries happen and I wanted to show people. I wanted to show people this is life and - I'm not going to wrap it in cotton wool - this is my life.''

Her attitude sums up that of the participants, most of whose commitment has remained steadfast. One family was absent for Life at 3, but returned for Life at 5. A second family chose not to participate in this series.

''People are incredibly open,'' Peedom says. ''If they tell you things, they do that because they trust you with it. You need to make sure in the end you don't betray that trust.''

Life at 7

Tuesday, ABC1, 8.30pm