This Article proposes that modern child custody law should be reassessed in light of recent scientific findings. Judicial determinations of custody use the "best interests of the child" rule. The rule is justified to a large extent by the goal of maximizing child developmental outcomes. The assumption is that a child whose "best interests" are protected stands a better chance of becoming a socially well-adjusted, productive and prosperous citizen.

Recent child development studies have shown that so-called "shared environment, "or home environment factors have little effect on child development so long as the shared environment is minimally adequate. Genetics and "non-shared environment" have a far greater influence on child development outcomes. While other reasons for the "best interests" rule may ultimately justify it, maximizing positive child development is not a justification supported by science.