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

While at the till in a clothes shop, Ruby received a call. She recognised the woman’s voice as the genetic counsellor she had recently seen, and asked if she could try again in five minutes. Ruby paid for her clothes, went to her car, and waited alone. Something about the counsellor’s voice gave away what was coming.

The woman called back and said Ruby’s genetic test results had come in. She did indeed carry the mutation they had been looking for. Ruby had inherited a faulty gene from her father, the one that had caused his death aged 36 from a connective tissue disorder that affected his heart. It didn’t seem the right situation in which to receive such news but, then again, how else could it happen? The phone call lasted just a few minutes. The counsellor asked if Ruby had any questions, but she couldn’t think of anything. She rang off, called her husband and cried. The main thing she was upset about was the thought of her children being at risk.

Over the next few weeks, she...