<p>I posted elsewhere --but don’t have the time right now to cross link – but this whole thing is garbage because finger length is GENETIC – it is influenced by hormones, but primarily your finger length/ratio is a matter of the genes inherited by parents. It’s a matter of interplay between dominant/recessive genes that are expressed somewhat differently depending on hormonal levels during development. Because it is genetic, finger ratios vary considerably by geography – with northern Europeans tending to have much shorter ring fingers than, say, Africans. There is no way that they can conclude that differences in performance are hormonally related, vs. a product of genetics, without controlling for the genetic factor: i.e., measuring the finger ratios of parents and obtaining info about parental performance on similar tests. </p>
<p>As I posted before, I am blessed with long tapering fingers with the ring finger clearly longer than index finger – a trait that was clearly inherited from my mom and her relatives, and which is shared by my brother and my offspring. My son is good in math, my daughter isn’t. Everyone always comments on our hands. </p>
<p>(You can find the links to the references I cited about genetics by either searching my other posts on the topic or going to the wikipedia article on digit ratio and also googling, “digit ratio genetic” or something similar)</p>