Genetic counsellors are the professionals who advise on the results of tests for hereditary conditions, often after samples have been taken from foetuses in the womb as well as from the parents. Consequently they are often the first to know that the father isn’t the father. A study in America found that more than 95 per cent of them would not tell a man that the child wasn’t his. (Around 95 per cent of genetic counsellors are female, and you have to wonder if more men would be informed if more counsellors were male.)