Lay people often wonder at all the fuss about identifying the biological sex of an individual. They may recall a granny or midwife, immediately after a delivery, even in the dim light, declaring with ease that it’s a girl, or a boy, to the rejoicing crowd waiting eagerly outside the delivery room. When it is so simple, why are doctors, sports administrators and investigators making such a hue and cry about this? How do you identify the biological sex of an individual? What is this fuss about sex verification tests? Are they the same as gender verification tests? What are the ethical, legal and social aspects of these sex verification tests? I will try to answer some of these questions.