An anonymous reader quotes a report from The Guardian: Children inherit four times as many new mutations from their fathers than their mothers, according to research that suggests faults in the men's DNA are a driver for rare childhood diseases. Researchers studied 14,000 Icelanders and found that men passed on one new mutation for every eight months of age, compared with women who passed on a new mutation for every three years of age. The figures mean that a child born to 30-year-old parents would, on average, inherit 11 new mutations from the mother, but 45 from the father. Kari Stefansson, a researcher at the Icelandic genetics company, deCODE, which led the study, said that while new mutations led to variation in the human genome, which is necessary for evolution to happen, "they are also believed to be responsible for the majority of cases of rare diseases in childhood." In the study published in Nature, the researchers analyzed the DNA of 1,500 Icelanders and their parents and, for 225 people, at least one of their children. They found that new mutations from mothers increased by 0.37 per year of age, a quarter of the rate found in men. While the vast majority of new mutations are thought to be harmless, occasionally they can disrupt the workings of genes that are important for good health.