Western Undergraduate Psychology Journal


Vast similarities in ownership behaviour across species and age ranges have been used to support the notion of an innate basis for ownership reasoning. Using a twin study paradigm, this is the first study to investigate the extent to which genetic and environmental factors contribute to individual differences in ownership reasoning. 65 pairs of adult monozygotic (MZ) twins, and 16 pairs of same-sex dizygotic (DZ) twins completed a 24-item ownership questionnaire, which included items on (1) new ownership and (2) appropriate transfers of ownership. For both of these factors, it was found that MZ correlations were larger than DZ correlations. Univariate model fitting analyses indicated that genetic and non-shared environmental factors could account for all individual variation on the two factors, with shared environmental factors contributing non-significantly; heritabilities ranged from .36-.57 over both factors. The results support the notion that individual differences in ownership reasoning have a significant genetic basis. It is proposed that future research look into the many other facets of ownership reasoning, and to explore their relationship and mediation via genetically influenced traits.

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