In this week's program, aeronautical engineer Dr Lauren Burns finally finds out the identity of her biological father.

To the amazement of all, he turns out to be part of a particularly distinguished Australian family.

We join Lauren as she meets him for the first time – and gets to know her half siblings.

At the same time two other young women, also created from donor sperm, have been trying desperately to determine their biological inheritance. But for them, it's a world of pain and no easy answers.

Together their stories raise challenging ethical, medical and legal issues that few would have envisaged a generation ago.