Malaspina consulted a national registry of mental illness maintained since 1950. At the time, isolated reports suggested that the youngest children in families have the highest risk of developing schizophrenia, but the reason for the trend was unclear. After poring over the medical records of more than 87,000 people born between 1964 and 1976 – 658 of whom had been diagnosed with schizophrenia or closely related psychoses – Malaspina reached a startling conclusion. Whereas one out of every 121 children born to men in their late twenties had developed schizophrenia by the age of 34, one of every 47 children born to men age 50 to 54 developed the disease. In other words, after age 50, a man’s risk of having schizophrenic offspring seems to be more than twice that of a man who reproduces in his late twenties.