Genetic Predisposition and Infidelity: From Molecular Variation to Relationship Behavior—A Narrative Review

Trust and pair bonding are central to human social life, and their violation through infidelity carries a measurable psychological cost. Whether individual differences in such behavior are partly genetic remains contested, because the available evidence combines heterogeneous phenotypes with candidate gene designs of limited statistical power. This narrative review synthesizes genetic evidence on infidelity, pair bonding, responses to trust violation and indirect traits such as novelty seeking, grading it by evidentiary strength. Twin modeling of extrapair mating yields broad-sense heritability of approximately 62% in men and 40% in women, but this specific estimate has not been reproduced in a comparable sample and describes population variance, not individual causation. Reported associations for DRD4, DAT1/SLC6A3, OXTR, AVPR1A, and MAO-A are traced to well-characterized molecular substrates, whereas the behavioral associations are small, inconsistently replicated, and frequently drawn from adjacent rather than direct outcomes: meta-analysis does not support OXTR rs53576 as a correlate of close relationships, and AVPR1A RS3 findings reverse in direction across samples. The unresolved question is not whether genetic variation matters, but at what magnitude and through which measurable phenotype. Adequately powered, ancestrally diverse, and functionally validated studies are required before any predictive claim can be entertained.