Medicine, which I wouldn't be without, has also been a force for... less good. For example, if you look at our mishandling of the immune system, using antibiotics in children and avoiding infection, we've certainly increased the risk of asthma.

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.

We can't any longer have the conventional understanding of genetics which everybody peddles because it is increasingly obvious that epigenetics - actually things which influence the genome's function - are much more important than we realised.

Childhood depression tends to be more common in inner cities, being most frequently related to serious social deprivation, bullying, domestic violence, wartime experience and famine. It is, for example, a serious problem among children who are traumatised refugees.

I remember eating in school in the years after the Second World War. Most of my friends had miserable portions of Spam with an inedible, glutinous pudding served in containers we called 'coffins.' As a vegetarian, I had a lump of loathsome cheese and some bread.

I don't believe in regretting - one should try to move on. My mum was good at that. She was deeply in love with my father, and he died when I was nine. She remarried, and her second husband died, too. I saw the grieving process she went through. My mother had this way of moving on. It was a fine trait.

However pragmatic you are, it is very demanding being a new parent.