The Department of Agriculture estimates that Americans spend an average of $245,000 per child between birth and age 18. And then there’s the stress of small stuff like sharing my house with a three-foot-tall graffiti artist.

Children can be exhausting, isolating and expensive. So if they truly make us unhappy, why do we keep having them?

Our ancestors required big families for hunting and farming, but that’s not necessary in the 21st century. As a mother, I know I wouldn’t trade the experience for the world, but my years as a scientist made me curious about what research can tell us. I dug into the findings, and it turns out there’s a lot of evidence for how children affect the physical and emotional life of their parents and a myriad ways in which they can boost both our health and happiness.

Parenthood certainly doesn’t start as a cakewalk: Friends and I jokingly refer to the first three months as “100 days of darkness” while on call 24/7 in an endless cycle of feed, wipe, bathe, repeat. Yet we persevere, and that’s in part because of the way that nature tricks parents into adoring their tiny new minion.