Internal gestation and birth give mothers a strong cue of their parental status for an infant. However, these cues are not provided to men. This results in paternity uncertainty, where men cannot be entirely sure that an infant is their genetic offspring. This has a variety of effects on parental investment, with women investing more in their offspring than men. While many effects of paternity uncertainty have been examined, there is no known measure of paternity uncertainty, and thus manipulations of paternity uncertainty are rare. My research in this area aims to first create a measure of paternity uncertainty, then manipulate paternity uncertainty to examine the limitations and strengths of the psychological mechanism and its associated behaviors.