I am very skeptical that this is actually true... for one, because I have heard of the "If your ring finger is longer than your index finger, then you are A; if your index is longer than your ring, then B" in another context before that wasn't to do with orientation. I would like to see a reference to the study, know their sample size, method, and how statistically significant their result was.
As for my finger lengths, I can change how I hold my hand (still holding it flat) and change which one looks longer... so method is important.