The moment she was born, our daughter created a new group: my children. Just as suddenly, everyone else joined another group: not my children. Family, the most powerful and smallest us to which most people belong, carpets the world in a vast, undifferentiated them. This boundary can dampen our empathy for outsiders, especially when they might imperil our own tiny tribe. In a study published last year, psychologists tested this idea by approaching women in Tel Aviv to ask their opinions about Israel’s Eritrean immigrants. In some cases, they first described these immigrants as threatening; in others, they did not. Crucially, about half the women interviewed were carrying infants at the time, and about half were alone. Women with babies in tow reported harsher views of immigrants than those without—but only in the condition where the researchers had described them as threats.

Sometimes merely thinking about family can spark exclusionary attitudes. One 2012 study asked people to write about either a recent Thanksgiving dinner with family or a recent shopping trip. The researchers then measured participants’ willingness to dehumanize outgroups by asking them to endorse statements like, “Some people deserve to be treated like animals.” Participants who had just written about family time were more likely to agree.

I certainly felt myself become more protective during my wife’s pregnancy, but I’m pretty affable, and I can’t imagine that changing much now that I have a kid. To me, the risk is not that fatherhood will cause me to feel antipathy for outsiders, but rather that I’ll feel apathy towards non-family members—in essence, that caring for my daughter will make it harder for me to care about anyone else. Will I still be able to invest in my friends’ hopes or my graduate students’ tribulations when she needs me so much more than they do? I know what Kevin meant when he describes parenthood as heart-expanding. But by funneling our empathy into one person, it might contract us, too.

At issue here is a bigger question about the nature of empathy. Is it truly a finite resource, in which caring intensely for certain people leaves us unable to care about others? There is almost no research to answer this question. The closest psychologists have come is the study of “compassion fatigue,” a term coined by the nurse Carla Johnson in the 1990s to describe nurses so emotionally invested in their patients that their own mental health suffers. As she described it: “Human need is infinite. Caregivers tend to feel ‘I can always give a little more,’ but sometimes they just can’t help.”

Some scientists argue that tradeoffs like these are baked into the nature of empathy itself—which would mean that parenting really is an emotional seesaw, maxing out our investment in our children at the cost of our broader social connections. (If this is true, empathy might be a darker force than people often assume.) But other psychologists, myself included, follow emerging evidence to a different conclusion: Empathy is more flexible than it appears. This means that even when our care for others tends to falter, we can choose to build it back up—and that new parents might find ways to retain or expand their empathy for the world beyond their children.