Original ArticleDo parents favor their adoptive or biological children? Predictions from kin selection and compensatory models
Section snippets
Kin Selection Theory
Evolutionary reasoning predicts less favorable treatment of unrelated children, relative to biological children. These expectations derive from Hamilton's (1964) Kin Selection Theory, namely that altruistic interactions between individuals should vary with their genetic relatedness. Hamilton asserted that behaviors incurring cost to the self (e.g., altruism) could evolve if such costs were outweighed by the benefit, multiplied by the coefficient of relatedness. He reasoned that natural
Fullerton virtual twin study
Participating families were enrolled in the Fullerton Virtual Twin Study (FVTS). The FVTS, ongoing since 1991, gathers behavioral, physical and health-related data on virtual twins and their families.
Four strict criteria decided if a given sibling set qualified as a virtual twin pair for the study. These criteria were generated with a view toward replicating ordinary twinship as closely as possible.
- 1.
Both children must be in the home by one year of age. This rule is based on the knowledge that
Results
For descriptive statistics, means and standard deviations for IQ and for the selected ACL and CBCL scales were computed for the full sample and for the VT pairs according to relationship status (adopted, biological). These data are displayed in Table 3.
Summary of findings
The present study compared mental ability and externalizing behavior in a unique sample of unrelated sibling pairs, with reference to different, but related theoretical frameworks. The key finding from Part I was that being an adopted or biological child does not predict ability-related or conduct-related behaviors. The exception was IQ in which the biological children significantly outscored the group of adoptees. However, this measure, while known to the parent, was obtained by an independent
Acknowledgments
This work was supported, in part, by the National Science Foundation (SBR-9712875), and CSU Fullerton faculty awards to the first author. The virtual twins and their families are gratefully acknowledged for their participation and support. This work was completed, in part, while the first author was in residence at the Singapore Management University, in Singapore, January 2013. Several colleagues and several anonymous reviewers completed critical readings of the manuscript prior to submission.
References (57)
- et al.
Paternal care by genetic fathers and stepfathers I: Reports from Albuquerque men
Evolution and Human Behavior
(1999) - et al.
Child abuse and other risks of not living with both parents
Ethology & Sociobiology
(1985) Differential parental investment in families with both adopted and genetic children
Evolution and Human Behavior
(2009)- et al.
Game theory and human evolution: A critique of some interpretations of experimental games
Theoretical Population Biology
(2006) - et al.
Just one g: Consistent results from three test batteries
Intelligence
(2004) - et al.
Who keep children alive? A review of the effects of kin on child survival
Evolution and Human Behavior
(2008) Twins: The finest natural experiment
Personality and Individual Differences
(2010)- et al.
What virtual twins reveal about general intelligence and other behaviors
Personality and Individual Differences
(2012) The Achenbach System of Empirically Based Assessment (ASEBA): Development, findings, theory, and applications
(2009)Darwinism and human affairs
(1979)
Relatedness and investment in children in South Africa
Human Nature
Older parent adoption
Older, wiser, and warming bottles
Adoptive families
Automaticity of social behavior: Direct effects of trait construct and stereotype activation on action
Journal of Personality and Social Psychology
Parenting and child development in adoptive families
Intercountry adoption
Specific cognitive abilities
How hungry is the selfish gene?
The Economic Journal
National ART success rates
The biological foundations of organizational behavior
Discriminative parental solicitude: A biological perspective
Journal of Marriage and Family
The Darwinian psychology of discriminative parental solicitude
Nebraska Symposium on Motivation
Discriminative parental solicitude and the relevance of evolutionary models to the analysis of motivational systems
Prefácio
The relations between perception and behavior, or how to win a game of trivial pursuit
Journal of Personality and Social Psychology
IQ, scholastic performance and behaviour of sibs raised in contrasting environments
Journal of Child Psychology and Psychiatry
A theory of cognitive dissonance
Human sociobiology: A holistic approach
Cited by (0)
- 1
Currently in the Department of Human Development and Family Sciences, University of Texas, Austin.