The study is an abuse of statistics, and few legitimate conclusions can be drawn. The IQ variance of 3 points in the mean doesn't give anyone an advantage - the difference between an IQ of 100 and 103 is no where near as significant as a difference between 118 and 121 (start of the end of the curve) or between 88 and 91 (start of the beginning of the curve).

If the study shows anything, it shows that some kids are a little more average than others.

It is also true that statistical information about groups cannot be legitimately applied to individuals within a group. In other words, while first borns as a group (in this study's finite set) may have a mean (as opposed to average, or median) IQ advantage, there is no reason to infer that any individual first born will have a higher IQ than any individual non first born child.

This isn't science, its conjecture. And, this conjecture is turned into pandering and gossip by the media. Frankly, if your IQ is 103, you stand a rat's chance in hades of getting into an Ivy League School (unless your initials are GWB). If it's possible to get into Harvard with an IQ of 103, its quite likely you would get in with an IQ of 100 (other things being equal). Because there is negligible difference between the scores.

Consider: if the IQ test has 100 questions, a 3 point difference on the statistical aggregate of the scores is less than 1 right answer difference on 40% of one thousand participants' tests.

'A tale told by an idiot, full of sound and fury...signifying nothing."