So, there is a study which examines the relationship between the length ratio of the index finger (2D) to the ring finger (4D).
Males tend to have a lower ratio than females - so this means that the ring finger is longer than the index finger. This sex difference appears to be related to the effects of testosterone during the 8-12th week of fetal development.

So, of course, I'm checking out Frank's hands... I know it's just some guy's research but there are a whole bunch of theories associated with this observation.
For example, there appears to be a correlation between the 2D:4D ratio and placement memory. The relationship reveals that the higher the ratio, the higher the placement memory.
As well, for males, the lower the ratio, the more likely you are better at musical instruments, sports, and have a tendency to be a little more masculine (grunt grunt).
There may be a link to sex related traits as well. They have also noticed that lesbians who think of themselves as more masculine tend to have a ratio much like men (lower).

Of course, I'm not going to enroll Franklin in ballet class just because he has a higher ratio. Nevertheless, it would drive my hockey-happy brother and father-in-law crazy. We live in Canada after all.