However fit and well you feel, however good your genetic inheritance, nobody’s genes are perfect, because everyone carries an estimated 400 damaging gene variants and two disease-causing mutations. It’s not as bad as it sounds, though – many of the disease or damaged variants are unlikely to cause any harm to the carrier, and even though as many as one in ten people studied were expected to develop a genetic disease as a consequence of the variants, these are often very mild.

Read the original paper in the American Journal of Human Genetics.