In China, there are 6 boys born for every 5 girls; the result of an age old preference for sons combined with widespread use of sex selection technology.
It's tempting to ascribe son preference to culture and leave it at that. However, for an economist, "culture" is a lousy explanation. It has no only trivial predictive value. Will the preference for sons persist over time, or will it gradually fade away? Cultural explanations cannot say: culture simply is what it is.
Another problem with "culture" is that it can explain anything. People in Uttar Pradesh select for sons?" It must be their culture. People in Kerala don't select for sons?" It must be their culture. Since "culture" is compatible with any conceivable set of facts, it is not falsifiable.
From a scientific standpoint, theories that can, potentially, be proved to be false are the best type of theories. Why? It's impossible to prove that any theory about the world is true. For example, once upon a time, Europeans had a theory: "All swans are white". They believed it was true, because they had observed thousands of swans, and all of them were white. But, of course, it wasn't, as the Europeans discovered when they went to Australia.
Since we can never prove our theories to be true, the best we can do is develop theories with testable predictions, and test them. Try as hard as we possibly can to show that the theory is false. If the theory stands up to all of our tests, then we accept it - for now.
"Culture" as an explanation also violates what Eric Crampton calls "the first rule of the microeconomists club": methodological individualism. A good economic explanation starts with the choices of individual rational actors. It begins with the premise that people are, fundamentally, all alike - we want social status, reproductive success (or sex, anyways), economic security. What looks like differences in tastes are, in fact, differences in ways of achieving those fundamental goals that we all share.
For example, in the 1960s, children begged to have Hostess Twinkies in their lunches, because in a world where most moms stayed at home and baked, bought goods were scarce and hard to come buy, hence were a high status item. Now, children beg for home made cookies in their lunch, because in a world where most parents are too busy to bake, home made cookies are scarce and thus high status.
Methodological individualism states that the best economic stories explain the world in terms of the choices of individual rational actors, constrained by prices and incomes. Becker and Stigler's article De gustibus non est disputandum is a forceful statement of this position:
On the traditional view [what I am calling here "cultural explanations"], an explanation of economic phenomena that reaches a difference in tastes between people or times is the terminus of the argument: the problem is abandoned at this point to whoever studies and explains tastes (psychologists? anthropologists? phrenologists? sociobiologists?). On our preferred interpretation, one never reaches this impasse: the economist continues to search for differences in prices or incomes to explain any differences or changes in behavior.
The Becker-Stigler view does not imply that culture or preferences are unimportant. Rather, it is rallying cry for economic imperialists, a call for economists to take culture, preferences, and all of the other phenomena ignored by previous generations, and explain them using the tools of rational choice theory.
According to this approach, "culture" is the beginning of an explanation, not the end. Why is there son preference is some places and not in others? What are the advantages and disadvantages, the costs and benefits, of sons? How can son preference persist?
The phrase methodological individualism isn't used much these days - it doesn't even have a half-decent wikipedia entry. I don't think this is because the early critics of methodological individualism, such as Kenneth Arrow, won the day. Rather, I think it's a combination of factors. Methodology - what some would call ideology - gets little time in the economics curriculum. In judging the quality of research, technique -- identifying variation, nifty econometrics -- are more important than methodological purity. Behavioural economics came along, and was able to explain phenomena that the old-school Chicago approach couldn't.
That economics is more open to alternative types of explanation than it was 20 or 30 years ago is a good thing. Still, it behooves anyone contemplating a career in economics to know what counts as a good explanation, and why.