Post written by François Grosjean.
Bicultural people are characterized by at least three traits. First, they take part, to varying degrees, in the life of two or more cultures. Second, they adapt, at least in part, their attitudes, behaviors, values, etc, to these cultures. And third, they combine and blend aspects of the cultures involved. Certain characteristics come from one or the other culture whereas others are blends based on these cultures.
Thus, contrary to bilingualism where it is possible to deactivate a language and only use the other in particular situations (at least to a very great extent; see here), biculturals cannot always deactivate certain traits of their other culture(s) when in a monocultural environment. A Colombian-American bicultural, for example, blends aspects of both the Colombian and the American culture and this often comes through in both a Colombian and an American environment, however hard the person tries to adapt fully to the one or the other situation.
Contrary to general belief, bilingualism and biculturalism do not always go hand in hand. People can be bilingual without being bicultural (think of Europeans who use two or more languages in their everyday lives but who live in only one country and within one culture), and people can be bicultural without being bilingual (such as British expatriates who have lived in the United States for many years). But of course, many bilinguals are also bicutural; they use two or more languages in their everyday lives and they navigate within and between their different cultures.
People can become bicultural at different points in time. Children can be born within bicultural families or come into contact with a second culture outside their home or in school; adolescents may pursue their studies in another culture; and many adults emigrate to other regions or countries and slowly acculturate into their new culture (for an example, see here).
Cultures rarely have exactly the same importance for bicultural people; one culture often plays a larger role leading to cultural dominance (similar to language dominance in bilinguals). In addition, cultures can wax and wane in one's lifetime, become dominant for a while before taking a secondary role later on, and vice versa.
Bicultural people navigate along a situational continuum that requires different types of behavior: at one end they are in a monocultural mode since they are primarily with monoculturals. Here they have to deactivate as best they can their other culture(s). If their knowledge of the culture in question is adequate, and the deactivatation is sufficient, then they can behave in a monocultural way (e.g. hold a meeting according to the rules of that culture, deal with monocultural business partners, welcome acquaintances, etc.).
However, because of the blending component in biculturalism, certain attitudes, behaviors, feelings, etc. may not be totally monocultural. For example, biculturals often produce blends in their greeting behaviors such as when shaking hands with someone (how firm the handshake? at the beginning and at the end of the encounter?), greeting a woman friend with a kiss (who exactly? how many kisses?), and so on. Cultural blends can also be observed in hand gestures, the amount of space to leave between yourself and others, what one talks about, etc.
At the other end of the situational continuum, bicultural people are in a bicultural mode since they are with other biculturals who share their cultures. They use a base culture to interact in and bring in the other culture, in the form of cultural switches and borrowings, when they choose to.
Bilingualism expert, Aneta Pavlenko, gave me an example of Russian-American teenagers in Philadelphia who may spend Friday evening with their families laughing over a popular Soviet-era comedy and then go out on Sunday night together to see a new Hollywood blockbuster. They'll chat about the movie in English but slip in a few Russian adjectives or a reference to a popular character from a Russian movie.
Biculturals often say that life is easier when they are with other people with the same bicultural background as them. They can relax and not have to worry about getting things right all the time. They often state that their good friends (or dream partners) are people like them, with whom they can be totally at ease about their languages and their cultures.
Grosjean, François. The bicultural person: A short introduction. Chapter 12 of Grosjean, François (2008). Studying Bilinguals. Oxford: Oxford University Press.
Nguyen, A-M. & Benet-Martinez, V. (2007). Biculturalism unpacked: Components, measurement, individual differences, and outcomes. Social and Personality Psychology Compass, 1, 101-114.