Much of Freakonomics is concerned with the difference between nature—the genetic qualities with which a human being is born—and nurture—the environmental influences that shape a human being’s character and behavior. By studying the relative influence of nature and nurture in children, the book reaches some interesting conclusions about both, while also suggesting some of the strengths and weaknesses of economics itself.
In order to assess the relative importance of nature and nurture, Levitt and Dubner use statistical methods to imitate the format of a scientific experiment. Using data gathered by the Department of Education, among many other institutions, the authors apply “regression” analysis in order to understand the relationship between many different variables. With the data gathered by the Department of Education, for example, it’s possible to find subjects that are statistically identical, save for a few variables (for example, IQ, parents’ income level, etc.). By isolating these few variables, economists can mathematically test the strength of the correlation between the variables; in other words, they can determine if there is a positive or a negative relationship between the variables, or if the variables have no influence on one another. This process imitates the format of a science experiment by isolating specific variables, and studying how changes in one variable (the independent variable) correlate with changes in another variable (the dependent variable).
The results of Levitt and Dubner’s regression analysis suggest that nature and nurture both play some role in a human being’s growth and behavior. There are many situations in which the parents’ income and education level tend to “trickle down” to the child, regardless of the child’s genetics. For instance, when identical twins (i.e., children whose “nature” is identical) are adopted by different parents, the twin who’s adopted by the wealthier, more educated parents is more likely to go to college and get a higher-paying job. However, in the majority of the cases Levitt and Dubner analyze, nature seems to play the stronger role in determining a child’s academic success, future income level, health, happiness, and general development. Statistical analyses suggest that parenting methods, such as reading to one’s child, going to museums with the child, and spanking the child, have little to no correlation with the child’s development. On the other hand, parental qualities like education, age, and general optimism correlate strongly with a child’s development. This would seem to suggest that parents pass on their useful qualities to their children genetically (i.e., through nature).
The manner in which Levitt and Dubner reach their conclusions about nature’s superiority to nurture suggests some of the conceptual weaknesses of economics, however. Levitt and Dubner have no way of studying how, exactly, genetics influences human development; only biologists and geneticists can provide those details. Indeed, the only way that Levitt and Dubner can determine that genetics plays a greater role in human behavior than nurture is by process of elimination: i.e., the fact that parental behaviors don’t play as large a role in child development would seem to indicate that genetics do, without explaining exactly how. Furthermore, Levitt and Dubner are forced to admit that statistical analysis cannot predict how people are going to behave in the future; in other words, there is always an element of randomness that no analysis of nature or nurture can account for. For instance, a child with a good education and loving, wealthy, educated parents could still turn out to be a serious criminal for reasons that no statistical analysis could reveal (and in fact, one such child, Ted Kaczynski, grew up to be the Unabomber, a notorious terrorist). So even if economics can use mathematics to suggest that nature plays a greater role in human behavior than nurture does, the limits of economics itself might—by Levitt and Dubner’s own admission—cause us to take this hypothesis with a grain of salt. To understand human behavior, we need economics—but we also need genetics, anthropology, history, and many other areas of study.
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Nature vs. Nurture Quotes in Freakonomics
Growing up in a single-parent home roughly doubles a child’s propensity to commit crime. So does having a teenage mother. Another study has shown that low maternal education is the single most powerful factor leading to criminality.
In other words, the very factors that drove millions of American women to have an abortion also seemed to predict that their children, had they been born, would have led unhappy and possibly criminal lives.
So even for someone who considers a fetus to be worth only one one-hundredth of a human being, the trade-off between higher abortion and lower crime is, by an economist's reckoning, terribly inefficient.
The typical parenting expert, like experts in other fields, is prone to sound exceedingly sure of himself. An expert doesn't so much argue the various sides of an issue as plant his flag firmly on one side. That's because an expert whose argument reeks of restraint or nuance often doesn't get much attention.
A long line of studies, including research into twins who were separated at birth, had already concluded that genes alone are responsible for perhaps 50 percent of a child's personality and abilities.
What appears to be an advantage gained by going to a new school isn’t connected to the new school at all. What this means is that the students—and parents—who choose to opt out tend to be smarter and more academically motivated to begin with. But statistically, they gained no academic benefit by changing schools.
The data reveal that black children who perform poorly in school do so not because they are black but because a black child is more likely to come from a low-income, low-education household. A typical black child and white child from the same socioeconomic background, however, have the same abilities in math and reading upon entering kindergarten.
There is a clear pattern at play: once a name catches on among high-income, highly educated parents, it starts working its way down the socioeconomic ladder. Amber and Heather started out as high-end names, as did Stephanie and Brittany.
The second child, now twenty-eight years old, is Roland G. Fryer Jr., the Harvard economist studying black underachievement.
The white child also made it to Harvard. But soon after, things went badly for him. His name is Ted Kaczynski.