There has been a lot of these types of research papers around for quite a while now discussing the relationship of finger length difference and androgen exposure. The abstract I’ve pasted below is one of the latest. I don’t have the full text article but it sounds interesting.

 

Authors McIntyre MH.

Institution Department of Epidemiology, Harvard School of Public Health, 677

Huntington Avenue, Boston, MA 02115, USA. mmcintyr@hsph.harvard.edu Title

The use of digit ratios as markers for perinatal androgen action. [Review]

Source Reproductive Biology & Endocrinology. 4:10, 2006.

 

Since the ratio of the second-to-fourth finger length was first proposed

as a marker for prenatal androgen action in 1998, over 100 studies have

been published that have either further tested the association between the

digit ratio and prenatal androgens, or employed digit ratios as a marker

to investigate the association between prenatal androgens and a variety of

outcomes, including behavior, fertility, and disease risks. Despite the

clear demand for an adult marker of prenatal androgen action and increased

use of digit ratios as such a marker, its validity remains controversial.

This review (1) evaluates current evidence for the relationship between

digit ratios and prenatal androgens (using experimentation with animal

models, amniotic testosterone, and congenital adrenal hyperplasia

case-control studies), (2) describes opportunities for future validation

tests, and (3) compares the potential advantages and disadvantages of

digit ratio measures with more established methods for studying the

effects of prenatal androgens. [References: 86]