ABSTRACT
What are the major factors which come together to make a good athlete? Here we suggest that foetal “programming”, and in particular the organisational effects of prenatal testosterone, is important in the aetiology of athletic ability. “Programming” describes the processes whereby influences during critical periods of early development permanently change the structure and function of the body. One important organisational influence on the foetus is that of sex steroids such as testosterone and oestrogen. The uterine environment is difficult to access and it is not possible to measure directly an adult’s exposure to prenatal sex hormones. What is required is a “window” into foetal sex hormone concentrations. The ratio between the length of the 2nd (index finger) digit and 4th (ring finger) digit (the 2D:4D ratio) may provide such a window (Manning, 2002).
