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Why Economists and Parents Need to Discover Behavioral Genetics

Behavioral genetics' lessons for economists and parents.

I'm Bryan Caplan, an economics professor at George Mason University, and a blogger for EconLog. I'm delighted to join the bloggers at Psychology Today. The long-standing rivalry between economics and psychology is happily fading away. That's especially good news for me, because my work sits at the intersection of the two fields.

Most of my research is what I call "behavioral political economy" - building models of politics using realistic assumptions about how actual voters think and feel. According to my first book, The Myth of the Rational Voter, the main reason that democracy disappoints us is that voters have good intentions but systematically biased beliefs about what works. Some of my other articles try to convince economists to take personality psychology seriously, abnormal psychologists to take basic microeconomics seriously, poverty researchers to take human irrationality seriously, and political economists to take intelligence seriously.

Over the last two years, though, psychology has almost taken over my life. To write my latest book, Selfish Reasons to Have More Kids: Why Being a Great Parent Is Less Work and More Fun Than You Think, I immersed myself in adoption and twin research, also known as "behavioral genetics." Of course, any field can use these classic techniques for disentangling nature and nurture. But intelligence and personality researchers were the pioneers and remain the market-leaders.

But why would an economist care about the nature-nurture question? Simple. Economists like Nobel laureate Gary Becker have been studying the family for decades. Like most modern parents, economists usually take it for granted that "parental investment" has large, lasting effects on adult outcomes. And yet adoption and twin researchers find surprisingly little evidence for this this assumption! With a few notable exceptions, the measured effect of upbringing on adult outcomes is small to zero. Adoptees barely resemble their adopting families, identical twins are much more similar than fraternal twins, and identical twins raised apart are often as similar as identical twins raised together. Almost all traits run in families, but the overarching reason is heredity.

The economics of the family is therefore based on a mistake. Contrary to most economists, high parental investment and small families aren't the key to adult success. If this mistake were confined to the Ivory Tower, though, the social harm would be small. A much more troubling implication of behavior genetics is that families make the same mistake when they decide how to raise their kids - and how many kids to have!

Modern parents push themselves very hard. Moms today spend more time parenting than they did during the Baby Boom, despite the fact that more moms work outside the home, despite the fact that family size has fallen, and despite the fact that dads do a lot more than they used to. The obvious cost is that parents end up making a lot of sacrifices that don't pay and neither parent nor child enjoys. The hidden cost, which inspires the title of my new book, is that people are needlessly scared to have kids.

I know that behavioral genetics remains controversial, even in psychology. Like all research, it's imperfect and has its share of blind spots. One of my goals in Selfish Reasons to Have More Kids was to fairly air this dirty laundry. But the main problem with behavioral genetics, in my view, is that researchers don't try very hard to reconcile science and common sense. My next posts will try to do just that.


About the Author

Bryan Kaplan, Ph.D.

Bryan Caplan is a Professor of Economics at George Mason University and the author of Selfish Reasons to Have More Kids: Why Being a Great Parent Is Less Work and More Fun Than You Think.