Being interested in writing, caligraphy, pens and what not as I am, I've looked into this stuff. They find a percentage of people, above 50%, who both write in a certain manner and also act a certain way and then say it means something. I don't think it has much baring really.
That's also because my writing changes, I have like 5 different styles of writing. Reading something I write by hand is hard if you're not use to it. It's like 5 different people wrote it.