Math / Writing skills based on the length of your finger!

Honestly, bro, I feel that there's no difference in what you've stated. You said that, "if their index finger is shorter than the ring finger, the child is better at writing/communication than mathematics skills," and "if the ring finger is longer than the index finger, Mathematics is a more dominant subject over writing/communications." If you'll truly closely and carefully analyze or scrutinize these two statements, it would be readily apparent that they're basically the same. If the index finger would be shorter than the ring finger, the natural equivalent of which is that the ring finger is longer than the index finger (though stated differently) and, thus, there's no real difference between these two statements. If this is the case, modesty aside, I would dare claim that I excel in both, since my index finger is shorter than my ring finger, which, as you've claimed, means that one is better at writing/communication, and my ring finger is longer than my index finger, which, as you've also claimed, means that one is better at mathematics.

I don't know i always thought that i'm a better mathematician than a writer but my fingers says its the other way around...

I started reading that as well and I think it is a bunch of bull harky. I think how well you do in certain subjects depends on who you are, and how you study, and how you are supported by your parents in your education. If you have people around you who help you learn, who teach you well, and reinforce what you've learned, you'll do better, that simple.