As a result, Dubé recommends starting a conversation with open-ended questions. Family members who are concerned about their relatives’ hesitance toward vaccines, she says, might start with questions such as, How did you start questioning vaccines? What makes you uncomfortable about them? Have you had something bad happen to you that you believe was the result of a vaccination? The crucial first step, she says, is to “get at where this is coming from.”

And it’s important to remember, Dubé adds, that many people on both sides of the vaccine controversy are profoundly influenced by emotionally moving personal narratives about the consequences of vaccinating or not vaccinating. And many of the most charged narratives, she says, come from parents who tell of “adverse events that are assumed to be due to vaccines … People tend to see those stories and relate to the parents telling them.”

Read: How story trumps science when it comes to anti-vax beliefs

Sure, “there are cases of parents [whose] kids died of a vaccine-preventable disease, and they can share their story,” which would support the pro-vaccination point of view, Dubé says. But the majority of people whose lives have been positively affected by vaccines have no disturbing or inspiring story to tell, because, as Dubé puts it, when vaccines work, nothing happens—and that’s good news.

Compelling narratives can also have a much more potent effect on a listener, Dubé says, than a deluge of statistics and scientific facts. One of the worst things family members who disagree over vaccinations can do to one another is engage in what she calls “facts ping-pong,” in which “you push one side, and then the other will reply with, ‘Well, I saw this video on YouTube, and it showed blah blah blah.’”

“I think it’s really an emotional topic, much more than a scientific topic. And those people who are questioning vaccines, it’s kind of part of their identity,” Dubé continues, noting that populations that doubt the efficacy or safety of vaccines—despite plentiful, credible evidence that demonstrates both—often mistrust government or medical authorities on other subjects, too.

Of course, these tense family arguments get only more stressful when the actual safety of one or more relatives is, or is believed to be, at risk. One Manhattan parent told the New York Post, for example, that he’s refusing to attend his family’s annual gathering for fear of exposing his two kids, the younger of whom is eight months old, to their unvaccinated cousin during a measles outbreak. “Besides my child getting [measles], I don’t want to be the one who gives it to their kid. The virus can be on me. If I hug their kid, I can transmit it,” he told the Post.

However, fear of endangering someone they love is actually one of the few things that Dubé has seen change vaccine skeptics’ outlook. For instance, in one study she found that pregnant women were more likely to consent to being vaccinated when they considered it a protective measure on behalf of their fetus, rather than on behalf of themselves. She also recalls an interview she did with a woman who had refused to let her newborn baby’s vaccine-skeptical grandparents visit unless they’d had a flu shot, for fear that they might pass the flu virus along to the baby. Upon hearing that, the grandparents relented.