The psychologists couldn't ignore the 107 children whose IQ seemed to fluctuate wildly across a twelve-year time span. Was this evidence, after all, that IQ is not so stable? To complicate matters more, the fluctuations in children's scores did not follow a simple pattern. Some scores dropped precipitously, while others seemed to surge upward. Perhaps IQ was more malleable than people thought. Then the psychologists took a closer look.
They realized that most of the kids whose scores got markedly better or worse during the study actually ended up about where they started. Among those 107 were children whose scores rose between the time they were five and eight but then dropped between the age of eight and adolescence. By the time those 107 children were in their teens, they had almost all returned to their original baseline scores. If you had tested a child only twice, you might see a surprising gain or loss in IQ. You might think you had found proof that children can lose their intelligence or get smarter. But the beauty of the Dunedin study was that researchers showed that over the long haul of childhood and adolescence, while there might be peaks and valleys, kids pretty much test where they began. If a child's IQ stays the same, the question is why. Is it because, like eye color, intelligence is inherited, or is it because, like taste in food, what you experience when you are little becomes imprinted on you? Just the fact that something is resilient doesn't tell you much about where it comes from.
Anyone who has adopted a child knows the quiver of uncertainty, however subtle, that makes you wonder whether your baby will "turn out" like you or like the biological parent neither of you will ever see. Karen had given birth to two children with her first husband and now wanted to raise a child with her second husband, a powerful creative director of television programs. They adopted Maude before she was even born. Karen was there for the birth and cut the umbilical cord, wrapping Maude up and giving her her first bottle. Neither Maude nor Karen saw the biological mother again. When Maude was little, she was full of energy, and she learned her first words before she was fourteen months old. She had a sparkle in her eye and a loud, happy laugh, and she seemed surprisingly like her father.
She even looked like him. They doted on Maude, filling her life with toys, interesting trips, stories, friends, good food, and books. When Maude was a preschooler, she seemed every bit her parents' daughter. So Karen and her husband weren't sure what to make of it when Maude began to have trouble in school. She loved the work, was eager to try everything, and carried herself like someone who thinks she is at the top of her class. Then it was time for her to be tested, because her parents wanted to send her to a private high school, which required an aptitude test. Although she had seemed so bright and adept during her first years of school, her parents were confused and dismayed to learn that Maude's scores were very low, much lower than their own or than those of Karen's biological children from her previous marriage. Although in so many ways she was like her parents, her IQ was not. How could this be?