The project sought to understand the factors which underlie cultural transmission, adapting self-reported methods from cross-cultural psychology and sociology to test the external validity of several constructs from existing evolutionary models. The target population were native-foreigner mixed-couples, allowing the analyses to benefit from asymmetrical cultural inputs. Sampling took place in Italy and Portugal, with recruitment relying on social networks, online newspapers, friends, organizations, universities, parishes, and embassies. The questionnaire was personally delivered or filled online. The validated variables were: contact with a population in which the majority endorses the culture being acquired, the relative quantity of friends from that culture, the perceived relationship quality with the companion, affective ties with one’s own family, and the desire and emotional components behind the culture-transmission motive (a concept similar to cultural conservatism). An unexpected strong, positive association between both cultural identities was found. Thus, it was suggested that these participants adopted an integrative orientation, allowing both cultural identities to blend, whereas most research so far focuses on assimilation scenarios. Overall, acculturation was driven by either conformity to the majority or random learning, without discarding the influence of preferred demonstrators, and the emotional bounds embedded in the individual’s cultural identity. Acculturation proved to be flexible and potentially changing according to the cultural trait being examined.