This kind of experimentation might explain evidence that younger siblings often live more adventurous lives than eldest siblings. They are more likely to participate in dangerous sports than eldest children and more likely to travel to exotic places, studies find. They tend to be less conventional in general than first-borns, and some of the most provocative and influential figures in science spent their childhoods in the shadow of an older brother or sister (or two or three or four).One could argue this is apparent in my family as well, with my brother having a unique sense of fashion, and being much more the world traveller than I am.
It's also interesting that there are two versions of the article on the NY Times site. They're both by the same author, and appear to be different revisions of the same text. Compare Study Say Eldest Children Have Higher I.Q.s with Research Finds Firstborns Gain the Higher I.Q..