Bearman and Bruckner: There is no fraternal birth order effect

Peter Bearman and Hannah Bruckner authored a paper in 2001 that was later published in the American Journal of Sociology, vol. 107, 1179-1205, 2002 which offers a major challenge to the recent fraternal birth order effect suggested by Anthony Bogaert. Bogaert’s research, published in the Proceedings of the National Academy of Science of the USA, suggests that having biological brothers, not non-biological ones (adopted, step-brothers) is the key to this effect, thus suggesting pre-natal factors, as yet undiscovered.

Those interested in this line of research should examine Bearman and Bruckner’s study which I believe to be very well done. They were also able to catch identical twin data and found low concordances for MZ, DZ and siblings. There were no significant differences between groups.

More on this paper later…