Explore the research on birth order. It's something we all like to believe, but as the textbook points out, "Many popular book...claim that firstborns tend toward achievement, middle-borns toward diplomacy and later-borns towards risk taking. Yet virtually all of these claims are exaggerated, because most researchers have failed to uncover strong or consistent associations between birth order and personality." Can you apply any of the principles of scientific thinking to these popular claims? Why do you suppose the idea is so popular?
I think one of the main reasons people want to believe/do believe in birth order is that they want a reason for how they are. People like know why things are the way they are and this is not an exception. Each of the birth order traits, tending for achievement, diplomacy, and risk-taking can all be construed in a positive way. One scientist, Frank Sulloway examined the association between birth order and attitudes towards revolutionary scientific theories, and found correlations between 4000 scientists, their birth orders and their reactions to those scientific controversies. This is one of the reasons birth order has risen in popularity, but unfortunately it hasn't quite held up against scrutiny. Some of the biggest issues with is studies are that it could have been biased, the historians examining the 4,000 scientists may not have been blind to their birth order, and the results of his study have not been able to replicated by many other scientists. There is not enough empirical evidence to take birth order seriously, it has not been replicated in double blind studies. It also does not follow the scientific principle of skepticism, it's a rather extraordinary claim, whereas correlating the personality traits to DNA or changes in how the children are brought up could explain it just as well.