Birth order effects are like those things that you think you see out of the corner of your eye but that disappear when you look at them closely. They do keep turning up but only because people keep looking for them and keep analyzing and reanalyzing their data until they find them.
Judith Rich Harris (2009). “The Nurture Assumption: Why Children Turn Out the Way They Do, Revised and Updated”, p.42, Simon and Schuster
