Finger lengths and behavior: Is the 2D:4D index of interest in forensic medicine?

The relationship between the second and the fourth digit in the human hand, the 2D:4D index, is considered a putative marker of exposure to prenatal testosterone. Much research has been done in the attempt to associate the 2D:4D index and physical characteristics as well as cognitive skills and behavioral patterns. It has been suggested that these characteristics and behavioral patterns may be linked to high levels of testosterone. The basis for considering the 2D:4D index a marker of prenatal exposure to testosterone, and the influence of prenatal and circulating testosterone on behavior are reviewed. Furthermore, it is discussed whether forensic medicine may benefit from identification of a marker of behavioral predispositions. It seems that it is not possible to derive any valid information on predispositions from finger length ratio, however the field of 2D:4D research might benefit from forensic studies.