In the last few years, I've come to believe very strongly in personality as a key to understanding yourself and your relationship with others.

I've come across an article that I agree with and have seen work in person:

http://www.softwarebyrob.com/2006/08/20/personality-traits-of-the-best-software-developers/

Personally, I've seen the example of flaky people writing flaky code, where the invere is also true; solid people writing solid code.