Children are active evolutionary agents adapted to extract the maximum resources from their environment, argues evolutionary psychologist Maryanne Fisher. She reveals why parenting fads like “gentle parenting” or “tiger parenting” that promise perfect harmony inevitably fail; and how we might better design social policy to support families as they actually exist, rather than as we wish them to be.

The family tug-of-war

We tend to view the family unit through a lens of inherent altruism. Parents are providers, children are receivers, and the entire family structure is magically engineered for mutual cooperation. When conflict arises, like when siblings fight over a toy, or a child demands attention at the expense of a parent’s exhaustion, we often treat these moments as aberrations, failures of discipline, or developmental hiccups to be smoothed over with the right technique. “If only I were better at applying gentle parenting methods,” a mother might think, “then my children would be so much better behaved!” 

However, evolutionary biology offers a starkly different, and perhaps more uncomfortable, perspective. Far from being passive recipients of care, children are active evolutionary agents adapted to extract maximum resources from their environment. In the context of the family, that environment includes, at its center, the parent. This parent-offspring conflict, as it is called, suggests that children are biologically predisposed to seek more investment than parents are predisposed to give, and to secure resources from siblings even at the expense of those siblings’ well-being. Understanding this biological reality is not an exercise in cynicism. Rather, it provides a powerful framework for making sense of family tension. It explains why parenting fads that promise perfect harmony inevitably fail, why sibling rivalry is so persistent, and how we might better design social policy to support families as they actually exist, rather than as we dream or wish them to be.

The economics of genes

To understand why a child might act against the interests of their parents or siblings, we must look at the genetic arithmetic involved. In the 1970s, biologist Robert Trivers formalized the theory of parent-offspring conflict. The logic is rooted in genetic relatedness. A parent is equally related to all their biological children (sharing approximately 50% of their genes with each). Therefore, from the parent’s evolutionary perspective, resources should generally be allocated in a way that maximizes the survival and reproductive success of all offspring collectively. Importantly, optimal allocation does not require an equal distribution of resources among children, since their needs and capacities differ across developmental stages. Parents may, for example, invest more (or less!) intensively in a vulnerable infant or support the educational pursuits of an older child, as circumstances warrant.

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Far from being passive recipients of care, children are active evolutionary agents adapted to extract maximum resources from their environment.

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The child, however, has a different calculation. While it might seem obvious, it is important to remember that a child shares about 50% of their genes with a full sibling, but 100% of their genes with themselves. While they have an evolutionary interest in their sibling’s survival, that interest is only half as strong as their interest in their own survival. Consequently, a child is naturally selected to demand more resources, such as food, attention, or protection, than the parent may want to provide, and to take those resources even if it incurs a cost to a sibling.