In the aftermath of the Boston bombings, many are asking how someone who came to America at the age of 9, attended some of our best schools, captained the wrestling team, went to the prom and became a citizen could have inflicted such a devastating attack on our society. The emerging evidence suggests that part of the answer is that no one in the past decade taught Dzhokhar Tsarnaev to love America, or at least did a very poor job of it.

But we know one thing for sure: He wasn’t taught that assimilation into American society was desirable. As I’m finding while researching a book on Hispanics — indeed, what I experienced as a young Cuban coming to this country in the early 1970s — we no longer teach patriotic assimilation. By that I mean love of country, not just its creature comforts.

We teach the opposite, in fact — that we’re all groups living cheek by jowl with one another, all with different advantages and legal class protection statuses, but not really all part of the same national fabric. In other words, we teach multiculturalism and diversity, and are officially making assimilation very hard to achieve.

If Dzhokhar and his brother Tamarlan are guilty of the acts of terrorism they are accused of because they succumbed to Islamist radicalism, then they are monsters who are personally responsible for turning against the land that welcomed them. Tamarlan has paid with his life, and Dzhokhar will be dealt judgment.

But as we grapple now with the thorny question of immigration, how to handle the millions of people who started to arrive at mid-century in a massive immigration wave, we could do worse than look at the affairs in Boston for a clue on whether our current approach works.

First let’s look at the brothers Tsarnaev. For a hint on their motivation we have no less an authority than their uncle Ruslan. Asked why his nephews had bombed the Boston Marathon, he replied with the now famous line, “Being losers, hatred to those who were able to settle themselves; these are the only reasons I can imagine of.”

In other words, failure to assimilate provided the fertile ground that allowed the bad seed of radical Islamism to take root. Ruslan’s reply resonates especially because it contrasts so greatly with his own view. Here’s what he said he teaches his own children: “This is the ideal micro-world in the entire world. I respect this country. I love this country. This country — which gives chance to everybody else to be treated as a human being.”

Then we have tweets that 19-year-old Dzhokhar, now clinging to life after a shootout with Watertown, Mass., police, has sent over the last few months. Two in particular display a disdain for the country that gave him refuge, sent him to the prestigious Cambridge Rindge and Latin Academy and gave him a scholarship to attend the University of Massachusetts.

On Nov. 6, the night of the elections, @J—Tsar tweeted out “america is impervious to the fxxkery #justforthisoneday. On March 14, 2012, Dzhokhar averred, “a decade in america already, i want out.”

As we can see, Dzhokhar had mastered the lingo of an American, but not the patriotism that once went along with it. As Peggy Noonan said in a prescient column in 2006:

“We are not assimilating our immigrants patriotically now. We are assimilating them culturally. Within a generation their children speak Valley Girl on cell phones. ‘So I’m like no,’ and he’s all ‘yeah,’ and I’m like, ‘In your dreams.’ “Whether their parents are from Trinidad, Bosnia, Lebanon or Chile, their children, once Americans, know the same music, the same references, watch the same shows. And to a degree and in a way it will hold them together. But not forever and not in a crunch.”

What’s even worse is that this state of affairs is the result of decision we made. We didn’t just get lazy and stopped teaching immigrants (and natives) to love America; we decided to stop and made assimilation a dirty word that connoted coercion and loss of ancestral culture. This despite all the evidence that assimilation, as preached and practiced since the nation’s founding, was not coercive nor did it demand an end to St. Patrick’s Day parades or love of Italian cooking.

In a retrospectively timely paper this month, the Hudson Institute reviewed evidence from a Harris Interactive Survey that showed that a large patriotic gap exists between naturalized Americans and native born. On such questions as to which should be the highest legal authority in the land, the Constitution or international law, or whether they considered themselves Americans or “citizens of the world”, native Americans saying the Constitution and U.S. citizen led naturalized Americans by more than 30 points.

“Why is there this large patriotic gap between native-born and naturalized citizens?” asked the Hudson researchers. “American leaders have essentially altered our de-facto assimilation policy from Americanization (or patriotic integration) to a multiculturalism that emphasizes ethnic group consciousness at the expense of American common culture. In short, we have sent immigrants the wrong message on assimilation.”

It wasn’t always so. We debated assimilation vs. multiculturalism in the 1910s, and chose the former. The Greatest Generation that ensued met Noonan’s “crunch test.”

Over the past few days, many people pondering the question of how the Tsarnaevs could have acted the way they did have discounted that lack of assimilation could be the case, emphasizing that the brothers Tsarnaev lived in Cambridge, “one of the most diverse and inclusive places in America.”

The problem is indeed with an “inclusive” approach that considers it wrong to teach love of a country so generous that it takes in two foreigners from a far-away land, gives them refuge, welcomes them in and gives them a free education. To have done so might have precluded the radical brain washing that led to the bombing.

Mike Gonzalez is vice president of communications for The Heritage Foundation.