Younger children rebel, eldest children defend the status quo.
Frank Sulloway of the Massachusetts Institute of Technology has spent 26 years gathering data on the effect of birth order on personality. His methods are objective. He has asked more than 100 historians to score thousands of historical characters - according to how revolutionary or reactionary the person was on various different measures. Then he painstakingly tracked down the birth order of as many as he could. Darwinists predict that siblings sometimes have to compete for their share of paternal investment.