It's fake, I've seen it on other places where they say it's fake as they post it. It's just a funny read.

I agree. I try to have my thesis that I'm working on backed up on least four different sources.

They have to do a lot of different kinds of tests to actually make a diagnosis. Here's the difference between normal and Marfan syndrome finger-wrist ratios: http://www.primehealthchannel.com/wp-content/uploads/2010/10/marfan-syndrome-hand.jpg
You're likely just fairly tall, but if your curious here's some information about it: http://www.marfan.org/about/signs
(I've been writing a paper on this for like 3 days straight)

So it's a genetic condition that affects how your muscles and bones connect to each other. Part of how they test for it is checking the ratio between the fingers and wrist, and they do it by having the person hold their wrist just like in this picture. People with it are typically very tall and lanky.