Psychology Ph.D. Dissertations

Why Do Mommy and Daddy Love You More? An Investigation of Parental Favoritism from an Evolutionary Perspective

Date of Award


Document Type


Degree Name

Doctor of Philosophy (Ph.D.)



First Advisor

Anne Gordon (Committee Chair)

Second Advisor

Eric Dubow (Committee Member)

Third Advisor

Richard Anderson (Committee Member)

Fourth Advisor

Jorge Chavez (Committee Member)


The current study examined the roles of parental certainty and offspring's ability to convert parental investment into fitness benefits for the parent (via social competitiveness) in predicting parental favoritism. Participants were college students who had at least one fully-biological sibling. Participants completed a series of on-line questionnaires that assessed their personal experiences regarding parental favoritism (or non-favoritism) with each biological parent. Additionally, they completed questionnaires that assessed their levels of health, intelligence, ambition, physical attractiveness, and parental resemblance relative to their sibling. As expected, results indicated that paternal resemblance predicted paternal favoritism, whereas maternal resemblance did not predict maternal favoritism. Additionally, in partial support of a hypothesis, fathers were shown to demonstrate favoritism in more specific areas than were mothers. Contrary to predictions, health, offspring intelligence, ambition, and physical attractiveness did not consistently predict parental favoritism. Discussion centers on the implications of the findings, offers possible explanations regarding why certain expected results were not obtained, and makes recommendations for future research.