Both in Britain and America, huge publicity has been given to stem cells, particularly embryonic stem cells, and the potential they offer. Of course, the study of stem cells is one of the most exciting areas in biology, but I think it is unlikely that embryonic stem cells are likely to be useful in healthcare for a long time.

Women of child-bearing age steadily run out of eggs by the continuous process of cell death. While reading a copy of the Guardian carefully from cover to cover, a normal woman will have lost on average two eggs - while, typically, a normal man will have made 70,000 new sperm.

My father died when I was nine, but I came from a stable family environment, which I think does contribute to being well-behaved.

Parents should talk to their children, even when they are babies and can't talk back.

You can now modify the genes of large animals, and the largest animal we are concerned with is the human.

The trouble with climate change is it's an extraordinarily diverse and complex issue, but for example if the BBC would let me make some of the programmes I'd like to make on climate change, I bet you there would be a change of emphasis.

A young woman in her teens has about 300,000 eggs in her ovaries. By the time she is menopausal, none are left.