A couple of comments: (1)NO BIG DEAL: IQ is but one measure of intelligence. People with higher IQs are not necessarily known to do be more successful or happier in life because of a higher IQ. I also don't buy the premise that higher IQ means being smarter. Smartness is a subjective term and can have so many measures. You could have a higher IQ but poor social and personal skills. Are you any smarter than your brother who may have a lower IQ but be better at those skills and do better. Smartness cant really be measured if you think about it. Attempt like this to quantity it may have their own merits, but they do not give the complete picture. So no big deal as far as this finding goes IMHO. (2) IS THERE A GENDER FACTOR TOO?: I ask this with only the most academic of intentions but I wonder how gender dynamics plays into this in some societies, like ours, where boys are brought up to be the more "responsible" person in the family. So that give them an edge in any way? When a boy is brought up to be responsible and carry on his family "legacy" and girls to be part of another family, how does that impact, if it does at all, his smartness and IQ compared to that of his sisters. (3) EXCEPTIONS: I haven't had my IQ formally measured, and I dont think my siblings have either, but mine falls into the exceptions - this theory would turn on its head if I were to apply it to my family to measure smartness. (4)BUZZ: What a great way to get in touch with your siblings! (forwarding the article) :P ha ha ha