Distress in Response to Infidelities Committed by the Partners of Close Others 1It is journal policy that submissions coauthored by a current editor are handled by a guest editor. We thank Rainer Banse, who handled the current manuscript, for his efforts.

To test rival explanations for sex differences in distress over sexual vs. emotional infidelity, evolutionary psychologists have studied people's reactions to the infidelity suffered by close relatives, claiming that sex-of-target effects would support an evolutionary explanation but refute a sociocultural explanation. This paradigm was extended by comparing genetically related and unrelated targets in two cultures. Students (N = 566) in Greece and Germany reported how much infidelity committed by the partners of siblings versus friends would distress them. Sex-of-target effects were found, though they were limited to Greek participants and to genetically unrelated targets. Across targets, a sex-of-participant effect emerged, with men being more distressed by sexual (vs. emotional) infidelity than women. The results are discussed with respect to evolutionary and sociocultural theorizing.