Is this getting blown a bit out of proportion? The correlation with birth order is 3 points on an IQ test - for reference, texting has been shown to drop your IQ by as much as 10 points [1].

Much like a MBTI, this is probably useful in the broad sense, but should not be depended upon objectively.

[1]http://www.timesonline.co.uk/tol/life_and_style/education/st...