The parental investment hypothesis provides a parsimonious explanation for a wide range of sexually dimorphic traits and behaviors across countless species. In the human context, the hypothesis posits that in light of the differentially greater parental investment that human females provide to their offspring, they should be much more vested in the wellbeing of their children. Munchausen Syndrome by Proxy (MSbP) occurs when a caregiver feigns or causes a medical condition in a dependent (typically a child). In the great majority of cases, the biological mother is the perpetrator, which is thus deeply surprising from an evolutionary perspective. I propose that for a small sample of women (e.g., those suffering from specific personality disorders and who do not possess the necessary support from their husbands/partners), the parental investment hypothesis is usurped or subverted in the service of their narcissistic need for attention (especially from high-status male physicians). Hence, in the same way that infanticide can be explained from a Darwinian perspective (despite it being at first glance incongruent with kin selection theory), MSbP appears to be equally amenable to an evolutionary analysis. One can test the hypothesis by demonstrating that the sex-specificity of the disorder holds true irrespective of cultural setting and epoch. Furthermore, one can look at single-parental families (as a means of controlling for the otherwise differential access to children in dual-parent homes) to show that within this controlled environment, mothers will remain the greater perpetrators of MSbP.