Immigrants are indeed an ambitious bunch. Immigrants and their children are more likely to get college degrees than are all Americans, they’re more likely to believe that hard work will help them get ahead, and they are more than twice as likely to start businesses as natives.

But the book's evidence for the internal dynamics underpinning these trends tends to overly rely on anecdotes from individual members, such as a Chinese-American Survivor winner and or an Iranian-American confused for an Arab after 9/11. The authors’ examples of “typical American” parents are comical stereotypes—one “white American” mom catches her daughter smoking pot and makes her write a “poem of atonement.”

What the authors don’t mention are the heaps of counter-examples involving remarkable people who don’t belong to Triple-Package cultures. Take this description of one easygoing 1960s American family:

The “household, known as Pennyroyal Farm, became the center of a vibrant arts community in Staunton … ‘Musicians would come and crash there for a couple of weeks because they’d run out of money,’ … ‘They’d play great music, and then finally they’d move on.’ … ‘Margaret and Fletcher were sort of hippies before there were hippies.’

The child of these hippy-dippy parents, Margaret and Fletcher, is Francis Collins, an Anglo-American, an MD/PhD, and current head of the National Institutes of Health.

Finally, while the authors do convincingly illustrate that many immigrants have these three traits, and that these groups are successful, the correlation and causation problem remains unanswered. With the exception of the famous marshmallow test and willpower, they don’t explain how exactly the Triple Package elements lead to better outcomes.

The current research on insecurity and success, for example, cuts both ways. In a meta-analysis, the psychologist Roy Baumeister found that boosting self-esteem has not been shown to help academic performance. Meanwhile, a study of 500 students, academics, and workers published in the Journal of Personality and Social Psychology found that people who are more confident achieve higher social status, regardless of their actual abilities. So why tout insecurity when the current science on self-deprecation is still vague?

Similarly, in the impulse-control chapter, Chua and Rubenfeld note that, “one of the most remarkable things about impulse control is that it transfers over from one domain of life to another.” But studies have found that willpower is, in fact, finite. “A growing body of research shows that resisting repeated temptations takes a mental toll,” the American Psychological Association writes. “Some experts liken willpower to a muscle that can get fatigued from overuse.”

And though Chua and Rubenfeld do point out fear as part of the “insecurity” motivator in immigrant ambition, they underestimate just how big of a factor it is. In reality, two steps out of LaGuardia or LAX or whatever polyphonic airport greets them, many immigrants who lack English and connections are seized with an all-consuming terror of starving to death. Research on immigrants has revealed widespread fear in their communities, particularly among the undocumented. And this fear tends to be immediate and causal: If you get an 85 on a science test one day, the thinking goes, you'll be chewing on shoe leather the next day because the family's meager cash reserves will have somehow evaporated overnight. In another recent immigrant tome, Little Failure, the author Gary Shteyngart describes his father arriving home from work one day and raining blows upon him for not completing a set of math problems out of a Soviet textbook in time. In the same breath, the elder Shteyngart worries that his "German boss" will fire him and the family will need their three-figure savings to live on. This is not because of some triumvirate of ironman characteristics. It is plain panic over survival.