Social Learning Theory: “parental infidelity sends memorable messages to offspring about the greater acceptability of infidelity, which are internalized and used to construct offspring’s belief systems” Genetic confounding alert (!) https://www.psychologytoday.com/blog/fulfillment-any-age/201712/ingenious-way-predict-if-your-partner-will-cheat …
Potential heritability of sexual strategies/sociosexuality. Parents with genetic predisposition for lesser commitment/prone to infidelity also pass on those genes to their offspring. Not saying acceptance/attitudes may not also play a role, but it surely isn’t all social learning