Effects of hand preference on digit lengths and digit ratios among children and adults.

<bold>Background: </bold>Prenatal sex hormones may not exclusively determine effects of hand preference on digit ratios. Genetic determination is an alternative possibility.<bold>Aim: </bold>To study the likelihood of similar effects of hand preference on digit lengths and digit ratios.<bold>Methods: </bold>We selected similar numbers of left-handers and right-handers in samples of kindergarten children (N = 101, age range: 3.5-7 years) and adults (N = 189, age range: 17-28 years) and measured digit lengths (excluding the thumb) directly on the palmar hand.<bold>Results: </bold>Compared to right-handers, left-handers had longer digits and lower third-to-fourth (3D:4D) digit ratios among children, whereas an opposite pattern of handedness differences occurred among adults.<bold>Conclusions: </bold>Effects of hand preference on digit lengths and ratios might be genetically/ontogenetically determined. Also discussed are implications of this set of findings for digit ratio research. [ABSTRACT FROM AUTHOR]