Audience participation is usually one of the less welcome features of the Edinburgh Festival Fringe, when innocent theatregoers can find themselves part of the action.
But there was no hesitancy among audiences at a play commissioned by the Wellcome Centre for Medical Science when invited to act as an ethics committee to decide on regulating genetic selection.
Nicola Baldwin's play, The Gift, focuses on 16-year-old Annie Kay, who suddenly discovers she has Friedreich's ataxia, an inherited disease of the central nervous system caused by a single defective gene and which leads to progressive deterioration of co-ordination and muscle control.
Because of her suffering, her brother, who carries the gene, is determined not to pass it on. But his teenage son is devastated to learn that his existence is due to test-tube selection and fertilisation, and rejects his talent as a tennis player.
"You'd probably be in a wheelchair by now," his father tells him.
"I'd rather be myself," the son retorts.
Ian Muchamore, the Wellcome Centre's scientific communication officer, said: "We think it's very important to raise the level of public debate around human genetic issues. Wellcome funds a great deal of research in genetics. For that to progress into real benefit to humankind needs a consensus, and at the moment there isn't one."
Ms Baldwin herself warned it is easy to forget that genetics is not some abstract scientific topic, but about all of us. "We all have different opinions - what we need is to hear and participate in the arguments before decisions are made."
After each performance, members of Y Touring, Central YMCA's theatre company, stay in character to lead a debate on the right of a particular couple to screen out the Friedreich's ataxia gene, and also to screen out the gene which would make a son short, the father being sensitive about his below-average height.
Each debate has included scientists, for example from the Medical Research Council's human genetics unit, to ensure there is expert advice on what is scientifically possible and what is simply speculation. Many members of the audiences have supported the parents' right to select out the gene responsible for a crippling disease.
There were fears that if parents could select out genes, even more stigma would be attached to disabilities. In one audience, a wife and husband were shocked to find they had opposing views on the height gene. "They'd never discussed something as fundamental as this before," said Mr Muchamore. "Drama can raise emotional issues and ethical dilemmas in a way a report cannot."
* The Gift will move to Winchester, Leeds, Bristol, Darlington, London and Cardiff over the next ten weeks. For further details contact Y Touring, 0171 2 5755.