Fact or Fiction: Childfree Couples Are Happier Than Couples with Kids (2011)

Imagine this:

Send couple A to France for two weeks and couple B to Italy. Then ask the question: who had more fun?

Couple A thought they had booked a great hotel, but it turned out to be pretty crappy. Intermittent hot water, lack of services, no view. However, it is located next to an excellent patisserie that serves the best creme brulee they've had in their lives.

Couple B thought they would do mostly sightseeing, but they ran into a couple who was there for birdwatching. Turns out the area they chose was the home of a rare bird, and the other couple gets them so excited about it that it becomes a lifelong hobby... Etc etc...

Point being that if you can't logically compare who had more "fun" in the apples-to-apples situation here, how can you possibly say who is more "happy" in the apples-to-oranges situation of having kids versus not? There are just too many variables.

If people believe in a bonding effect, wouldn't weaker relationships be more prone to children?