Saw a fascinating show , where they used the relationship of the fourth finger as compared to the index finger. Scientists used only finger length to determine who would be best at certain skills. If you have a longer index finger you will most likely excell at writing, or literary skills, if your fourth finger is significantly longer you will excell at things like operating a backhoe, or other things that require good hand eye coordination. The results were remarkably close to what the scientists had predicted based on finger length.

http://en.wikipedia.org/wiki/Digit_ratio

http://www.bbc.co.uk/science/humanbody/sex/articles/testosterone.shtml