Black, Sandra E.; Devereux, Paul J.; Salvanes, Kjell G. - 2007
Norway that allows us to precisely measure birth order effects on IQ using both cross-sectional and within-family methods … explains about 3% of the within-family variance of IQ. When we control for birth endowments, the estimated birth order effects … birth order effects occur because later-born children are more affected by family breakdown. …
