The big idea: How much do we really want to know about our genes?

Ruby was at the till in the clothes shop. She asked the woman if she could try again in five minutes, after she recognised her voice as the genetic counsellor she had recently seen. Ruby paid for her clothes, went to her car and waited. The counsellor's voice gave away something.

The woman said that Ruby's genetic test results had come in. They had been looking for a certain type of genetic abnormality. Ruby's father died from a heart disease that was caused by a faulty gene he had. It didn't seem like the right situation to receive such news in, but how else could it happen? The call lasted a few minutes. The counsellor asked if Ruby had any questions, but she couldn't think of anything. She cried when she called her husband. She was upset that her children were at risk.

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Over the next few weeks, she searched, read, and tried to become an expert patient in a rare genetic disorder. It was hard for her to evaluate what she found because she wasn't a scientist. She learned that there was a link between the genes and the problems. This disease had not yet been named a few years ago.

There were some details that emerged over time. Nobody had ever seen her family's particular variation. It was difficult to know what to think of her situation. Nobody could say how much her risk of a heart problem had increased.

Every one of us will either be special or subtly suboptimal.
Ruby was not seen by any other medical professional until six months after the initial phone call. She saw a cardiologist first, followed by a series of other specialists. Ruby was told to take medication to lower her blood pressure as a precautionary measure, and she would have regular body scans. She was told to avoid anything that could cause her body to jerk. The vagueness of what this meant in practice became a source of worry. Should she continue to play basketball? She had always loved going abroad, but now travel insurance was hard for her because nobody knew how to classify her.

Ruby believes that it was a good idea to be aware of her genetic inheritance, because there were things she could do to lower the risk of it becoming a real problem. It took her a long time to realize that she was not ill. She was at risk of being sick. She had only become aware of a possible future and nothing had changed.

We are all susceptible to one illness or another. Many more of us will find ourselves in Ruby's situation as science progresses and we have to make difficult decisions about our health and how we live. Every one of us will be shown to be less than optimal. Every one of us will be shown to be special. It depends on how you look at it. Andrew Solomon writes that the general culture feels that children who lack hearing are the most vulnerable to deafness. The deafness culture feels like they have something.

As our ability to link genes with human traits expands, we must be very careful in defining what constitutes a disease or disability. In The Body: A Guide for Occupants, Bill Bryson says that 20 years ago about 5,000 genetic diseases were known. It is 7,000 today. The number of genetic diseases is constant. Our ability to identify them has changed.

Things get messy even in the hard data. A person with an immune system gene called HLAB 27 is about 300 times more likely to develop the disease ankylosing spondylitis. Most people in the UK don't suffer from this variant of the disease. inheritance of this gene may be useful in fighting HIV. About one in 300 people with HIV are able to control the virus so that they don't go on to develop Aids, and H27 occurs frequently in these people. Even for experts, it is hard to understand the balance of genetic inheritance.

One day, a watch that can measure a few simple things about your body will be seen as a primitive tool. In the future, a cloud of information will be available and you have to decide how much you want to look at it. The agricultural, industrial and digital revolutions affected our environments and societies, but the genetic revolution gave us new powers and each of us will need to decide if and when to use them. One way we can prepare is to make sure society is literate and that our children are educated to understand risk and health.

We are not just our genes, our cells, our brain, or our microbiome. We are all of these things, but we are more. The stories we tell and the philosophies we live by are going to be important to our wellbeing.

Daniel M Davis is a professor of immunology at the University of Manchester.

Further reading.

Andrew Solomon wrote Far from the Tree: Parents, Children and the Search for Identity.

The Body: A Guide for Occupants was written by Bill Bryson.

The Code Breaker is a book by Walter Isaacson.