Fact or Fiction: The Horde attracts the more mature player

I saw this thread in the WoW.com forums and the original poster is making a point that I have heard, consistently, since I started playing World of Warcraft. The point being that the Horde attracts the mature players and the Alliance is full of teenagers, griefers and whiny babies. In fact, the fellow is so annoyed he is leaving the Alliance and heading back to the Horde to avoid the alleged Alliance childish behavior.

I personally have not noticed this so much, or at least to the degree that a lot folks have. I played Horde for over a year, and the past 10 months have played Alliance, and I have seen immature behavior on both sides. While my time with the Alliance has seen a slightly higher population of jerks and immature babies, the biggest moron I have encountered was on the Horde side. And isn't it a bit strange that the most well-known example of stupidity in all of WoW, Barrens chat, is on the Horde side?

What do you guys think? Is the Alliance a haven for the immature and annoying? Or is the Horde just as bad, if not worse?