Editor’s Note: Cynthia Miller-Idriss runs the Polarization and Extremism Research and Innovation Lab (PERIL) at American University. Her book, “Hate in the Homeland: The New Global Far Right,” will be published in October by Princeton University Press. The views expressed here are her own. Read more opinion on CNN.

CNN  — 

“I don’t know what happened, I just know that the boy wasn’t raised that way.”

These are the words Dylann Roof’s father repeated to a journalist after his son was sentenced to death for the murder of nine African American worshippers in Charleston church. Law enforcement officials said Roof told investigators upon his arrest in 2015 that he’d killed the Bible study attendees to start a race war.

In fact, Roof’s radicalization pathway started with an online search that led him to a White supremacist website. In his manifesto and during interviews with law enforcement, Roof singled out the importance of that search, noting that he had “never been the same since that day.”

Related: 'United Shades of America'

  • For more on online radicalization and white supremacist extremists, watch “United Shades of America with W. Kamau Bell” Sunday at 10 p.m. ET.

    Parents whose children have perpetrated racist or extremist acts often respond with similar words; “He didn’t learn that from us!” or “Those aren’t our values!” are common refrains. White families may point to raising their children to be “colorblind” with statements that “everybody’s equal” without explicit conversations about race as their way of instilling “good values.”

    But as many experts have pointed out, silence about racism leaves White children to draw their own conclusions about the inequalities they observe or ignore them altogether. Values alone can’t always compete with what kids and teens encounter online.

    And with children having more time to spend online during the Covid-19 pandemic, there comes an increased risk of exposure to bad actors and extremist ideas.

    Extremists — who see the world as divided into hostile “us-versus-them” identity groups that are in dire conflict with one another — mobilized quickly during the pandemic and the nationwide protests for racial justice. White supremacist extremists have circulated propaganda and conspiracy theories about Covid-19 that wrongly blame immigrants or Asians and attempt to target Jews and the police. Some far-right extremists have exploited the George Floyd protests for their own goals, aiming to spark a civil or race war and working to incite violence at peaceful protests. A leader of the Virginia Ku Klux Klan is facing prosecution for a vehicle-ramming incident, one of dozens that have occurred since the protests began.

    Under ordinary circumstances, youth are already a vulnerable population for radicalization. Adolescents are prone to risk-taking and are in the throes of identity exploration, looking for answers to questions about who they are and who they want to be. They can be attracted to the sense of rebellion extremist groups offer as well as promises of belonging and purpose.

    But children and teens may be at an even greater risk for radicalization during the pandemic, as they may experience higher rates of anxiety, depression and isolation. To make matters worse, many kids have lost the networks of peers and adults — like teachers, employers and coaches — who might normally notice red flags in behavior.

    Parents and caregivers are now the primary adults who can recognize warning signs and intervene at early stages of radicalization — and there are several action steps they can take, even during a time when they are understandably overwhelmed with new caregiving challenges.

    Being aware of the risk is one place to start. Even before the pandemic, research from the Anti-Defamation League found that nearly a quarter of players were “exposed to discussions about white supremacist ideology” while gaming online. Gaining a solid understanding of how your kids spend time online is key, especially if it includes encrypted platforms, anonymizing apps or toxic online communities. (A list of sites, platforms and apps to look out for, along with a resource list for parents and caregivers, is available in this guide that my research lab helped create.)

    Parents and caregivers can be alert to key warning signs by listening to what children say. Kids who mention conspiracy theories or talk about “fragile” snowflakes not being able to take an anti-Semitic or racist joke have likely been exposed to extremist content, for example. But because responding with ridicule or punishment can drive youth further online, parents need strategies that go beyond shaming.

    More effective approaches include talking with teens and young adults about how they know information sources are valid, how online manipulation works, and how propaganda can be disguised as humor. Research shows that learning about manipulation in junk food advertisements reduces kids’ positive views of unhealthy food more than if they are taught about the consequences of poor eating habits alone. And research suggests the same is true for inoculating people against manipulation in terrorist propaganda.

    Preventing radicalization is not only about recognizing risk. Parents and caregivers can work to build resilience to extremist narratives by modeling kindness, empathy, and finding ways to give children a sense of control over their lives. Strengthening a child’s sense of positive identity can reduce vulnerabilities to extremist promises of belonging and purpose.

    Fostering deep engagement with a wide range of ideas and people is also important. Research shows that the more time people spend in like-minded groups the more likely they are to move toward extremes.

    None of this will work if White families stay silent about the legacy of structural racism in this country. Simply telling children that “we are all equal” when their Black and brown peers clearly have unequal experiences makes it harder for White children to recognize and challenge White supremacy. Open and ongoing conversations with White children about race and racism are critical.

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    This isn’t the first time we have faced increased risk of radicalization. After Barack Obama’s election as the first African American US president, there was a surge in the numbers of active hate groups and militias.

    But 2020 is unique in important ways. The vast and evolving ecosystem of toxic online spaces, combined with potentially unprecedented amounts of time online and increasing anxiety and isolation for some, have created a perfect storm for extremist recruitment. It’s on all of us to stop it.