The ratio of 2nd to 4th digit length: A new predictor of disease predisposition?

The ratio between the length of the 2nd and 4th digits is: (a) fixed in ute ro; (b) lower in men than in women; (c) negatively related to testosterone and sperm counts; and (d) positively related to oestrogen concentrations. P renatal levels of testosterone and oestrogen have been implicated in infert ility, autism, dyslexia, migraine, stammering, immune dysfunction, myocardi al infarction and breast cancer. We suggest that 2D:4D ratio is predictive of these diseases and may be used in diagnosis, prognosis and in early life -style interventions which may delay the onset of disease or facilitate its early detection. (C) 2000 Harcourt Publishers Ltd.