IStock Photo 4593417 © Jaren Wicklund

If conventional wisdom is to be believed, Angelina Jolie and Brad Pitt must be delirious, because having kids is supposed to be the key to happiness. They’re called bundles of joy, blessings from heaven—and most Americans plan to have them. 1 in 1.3 of all males (77%) and the same number of females of childbearing age who don’t already have biological children say they intend to have a child. And about 68% of women (1 in 1.46) in the same age bracket who have already had a live birth will go on to have a second.

Yes, Angelina does manage to look both blissful and elegant, but we’ve all seen our fair share of the flip side of parenthood: frazzled men and women, eyes red-rimmed from lack of sleep, leading their protesting flock through the grocery store check-out lane and looking, well, not ready for the paparazzi and a few pegs down from joyful. Are these people really more content than those without children? And what about the 1 in 2.22 women aged 15-44 who don’t have kids? Are they missing out on their chance for happiness?

The answer, as it turns out, is a resounding . . . maybe. According to a new study by Dr. Luis Angeles published in The Journal of Happiness Studies, children have a significant and positive effect on life satisfaction, an effect that only increases with the number of kids. This finding is contrary to several previous studies, including a 2005 examination of data gathered from 13,000 Americans by the National Survey of Families and Households. Responses to that survey showed that nonparents experienced less depression across the board than did people with children.

Why the differing results? For Dr. Angeles, it all boils down to circumstances. In his research, married couples of all ages (and married women in particular) report improved life satisfaction upon having a child. Adding more kids to the household only increases that sense of well-being. For unmarried individuals, however, including people who are single, separated, or living together as a couple outside of marriage, raising children is more likely to have a negative impact on happiness.

A recent and controversial finding indicates gender might also play a role in the relationship between parenthood and happiness. In a study of adult identical twins, Dr. Hans-Peter Kohler of the University of Pennsylvania found that fathers experience almost 75 percent more happiness upon the birth of a firstborn son than they do upon having a firstborn daughter, while a first child’s gender has little bearing on mothers’ happiness. However, also in contrast to the findings of Dr. Angeles, raising more than one child was found to have a negative impact on feelings of well-being for mothers (although they still report significantly greater happiness than their childless counterparts) but not for fathers, who reported no effect from adding second and third kids to their broods.

In the end, our cultural beliefs about having kids (namely, that doing so brings unparalleled joy) may make it difficult to truly measure the impact of parenthood on happiness. After all, while mothers and fathers are often quick to complain about things like temper tantrums and midnight feedings, most would be loath to admit that having their children has left them feeling anything less than fulfilled. Whether they are happy or not, most parents place their children near or even at the top of their list of the most important things in life—presumably well above a full night’s sleep or an uninterrupted dinner conversation.