I will be the first to admit that “Why do mothers care more about their children than fathers?” is not a very pretty question. But, before you answer with an angry “They don’t!”, note that it has been consistently shown that money given to mothers is far more likely to be spent in a way that benefits their children than is money given to fathers.
I raise this uncomfortable question for the following reason; if you care about the wellbeing of children, then the more that you believe that male and female roles in the family are biologically predetermined, the more you should be willing to support the idea of women working outside of the home. And, alternatively, the more that you believe that women’s caring role has been socially imposed the more you should be in favor of women staying in the home caring for children.
To see why, let’s start with the belief that greater maternal altruism is purely biological; that women have evolved over human history to care more than men about the welfare of their children.
If women are hardwired to care more about their children than men, then it must be true that children will be better off if their mother has more say in how household resources are distributed within the family. The most effective way for a woman to increase her say in how the family’s income is spent is by actively contributing to household income through waged employment. At the same time, the level of care from their mothers is unchanged relative to if she was not in the workforce, because that level of caring is biologically determined.
It follows that if maternal altruism is biological, freeing women to enter into the workforce should improve child welfare because maternal caring is not reduced and household resources allocated to children increases.
The alternative is that we believe that women demonstrate more altruism toward their children because women have been historically excluded from the workforce; the role of caregiver, as opposed to provider, has been societally imposed on women as a result of gender differences in earning ability.
If maternal altruism is not biological, then there is no reason why a mother who is a provider should care more about her child’s welfare than a father who is a provider. Given what we already know, this implies that children whose mothers are working will not benefit from her additional say in the allocation of household resources; she will be more selfish in her allocation than she would have been had she stayed out of the workforce.
It follows that if maternal altruism in not biological (and only if is not biological), freeing women to enter the workforce erodes child welfare because maternal caring is reduced and household allocation of resources to the child does not increase.
Ultimately, whether children are made better or worse of when their mother works is not subject to personal opinion nor is the question of why mothers care more than fathers. I am happy to leave the final say on that topic to this excellent paper, The Evolution of Altruistic Preferences: Mothers versus Fathers, by evolutionary economists Ingela Alger and Donald Cox.