1. Petter Kristensen and Tor Bjerkedal, “Explaining the Relation Between Birth Order and Intelligence,” Science, vol. 316, no. 5832 (2007), p. 1717.
2. In Galton’s story, daughters scarcely had a role to play—which also fitted the mores of his time. Galton later built up the less-than-illustrious reputation of being the founder of eugenics, the belief that the human race can be improved by selective “breeding.”
3. David W. Lawson, “The Behavioural Ecology of Modern Families: A Longitudinal Study of Parental Investment and Child Development” (PhD thesis, University College London, 2009), p. 30.
4. The desire to avoid splitting family property weighed more heavily than the need to allow each son to build up an autonomous existence. Naomi J. Miller and Naomi Yavneh, eds., Sibling Relations and Gender in the Early Modern World: Sisters, Brothers and Others (London: Ashgate, 2006), p. 3.
5. If there are two or three sons in a fairy tale, then you can be sure all hell’s going to break loose—and in particular that the youngest will be treated horribly by his elder brothers. The sociologist Lily E. Clerkx ascribes this to the early modern inheritance system: the first was the heir, the second could often marry a daughter with a dowry, but as the third son you got nothing. Lily E. Clerkx, En ze leefden nog lang en gelukkig. Familieleven in sprookjes. Een historisch-sociologische benadering [And they lived happily ever after. Family life in fairy tales. A historical-sociological approach] (Amsterdam: Bert Bakker, 1992).
6. The quote, from the historian Jack Goody, is taken from Clerkx, En ze leefden nog lang en gelukkig, p. 174.
7. Julia M. Rohrer, Boris Egloff, and Stefan C. Schmukle, “Examining the Effects of Birth Order on Personality,” Proceedings of the National Academy of Sciences, vol. 112, no. 46 (2015), pp. 14224–29.
8. Roger D. Clark and Glenn A. Rice, “Family Constellations and Eminence: The Birth Orders of Nobel Prize Winners,” Journal of Psychology, vol. 110, no. 2 (1982), pp. 281–87.
9. Daniel S. P. Schubert, Mazie E. Wagner, and Herman J. P. Schubert, “Family Constellation and Creativity: Firstborn Predominance Among Classical Music Composers,” Journal of Psychology, vol. 95, no. 1 (1977), pp. 147–49.
10. W. Scott Terry, “Birth Order and Prominence in the History of Psychology,” Psychological Record, vol. 39, no. 3 (1989), pp. 333–37.
11. Frank J. Sulloway, Born to Rebel: Birth Order, Family Dynamics, and Creative Lives (New York: Vintage Books, 1997), pp. 262, 324–25.
12. König, Brothers and Sisters, p. 26.
13. Nicholas C. Herrera et al., “Beliefs About Birth Rank and Their Reflection in Reality,” Journal of Personality and Social Psychology, vol. 85, no. 1 (2003), pp. 142–50.
14. Rodica Ioana Damian and Brent W. Roberts, “The Associations of Birth Order with Personality and Intelligence in a Representative Sample of U.S. High School Students,” Journal of Research in Personality, vol. 58 (2015), pp. 96–105.
15. Rohrer, Egloff, and Schmukle, “Examining the Effects of Birth Order on Personality,” pp. 14224–29.
16. Rodica Ioana Damian and Brent W. Roberts, “Settling the Debate on Birth Order and Personality,” Proceedings of the National Academy of Sciences, vol. 112, no. 46 (2015), pp. 14119–20.
17. Albert Somit, Steven A. Peterson, and Alan Arwine, “Birth Order and Political Behavior: Clearing the Underbrush,” International Political Science Review, vol. 14, no. 2 (1993), pp. 149–60, esp. p. 149.