parenting happiness

Parents here pay a steeper happiness penalty than elsewhere in the world.
Sharing childcare duties = better relationship?
The question of how parenthood affects happiness is one researchers have pursued for years -- with mixed results. A 2014
To those who believe that there is an inverse relationship between parenting and happiness, there is the parallel finding that these “parents find caring for their children to be much more exhausting than the work they do for pay.” So we are enriched by our kids, but all that enrichment can be tiring? Makes sense to me.
Children who carried the long version of the 5-HTTLPR gene seemed to be able to maintain a positive attitude in the face
We know intuitively that how happy we are -- in a relationship or otherwise -- affects our children.
Research suggests that parents hate parenting, so with all these built in challenges, is there something deeper besides just the evolutionary push that drives people to become parents?