Since the 1980s, economists and psychologists have been aware of a "parental happiness gap." Basically, the running theory has been that parents are a less happy bunch than their non-parenting peers. This makes some sense: After all, parents have a lot on their plates—changing diapers, getting their kids into the right schools, keeping their vaccinations up to date—and rarely have time to just relax and enjoy themselves.
But Chris Herbst of Arizona State University and John Ifcher of Santa Clara University noticed some weaknesses in earlier studies on the phenomenon. Why did the studies always treat the happiness gap as a constant? Also, why was the word parents always defined as people whose egg and sperm had met and created a child? This excluded a segment of society who chose to have children: adoptive parents, step-parents, relatives who take in children—non-biological parents who willingly (and many times, happily) take in children to raise because they want to and, perhaps, find joy in having kids around.
So Herbst and Ifcher turned to two surveys (the General Social Survey and the DDB Worldwide Communications Life Style Survey) to re-examine parental happiness by looking at both happiness trends and expanding the definition of “parents” to include any adult who has a non-adult living under the same roof.
For the rest of the story: http://www.theatlantic.com/business/archive/2014/05/do-kids-make-parents-happy-after-all/361894/