The disturbed individual who believes himself to be Christ, or to receive messages from God, is something of a cliche in our society. Ever since Sigmund Freud, many people have associated religiosity with neurosis and mental illness.

Following 25 children for the TV series 'Child of Our Time' has been extraordinary. The BBC's original plan was to commemorate the new millennium. What better way than to film a number of expectant mums from across the U.K.? Coming from widely different backgrounds, all were due to give birth on January 1, 2000.

I'm a traditional Jew with an orthodox background, and it informs much of my approach to science. Of course I think it's very important that if you have those sorts of backgrounds you don't impose them on other people as a clinician, of course.

Carbon dioxide is unusual because it doesn't go through the usual three phases of matter, from solid to liquid to gas, but it goes straight from solid to gas. The volume of the gas is much greater than the volume of the solid. When a solid turns into a gas, we say it sublimes. The process is sublimation.

I do not know of any credible evidence that suggests Dr Zavos can clone a human being. This seems to be yet another one of his claims to get repeated publicity.

Man is a competitive creature, and the seeds of conflict are built deep into our genes. We fought each other on the savannah and only survived against great odds by organising ourselves into groups which would have had a common purpose, giving morale and fortitude.

Over the past 20 years, I have presented many science programmes on BBC1. But none is, I think, more socially important, or of more human interest, than this ongoing series of 'Child of Our Time.'