Multicultural people are not just confined to having parents from two different cultures. There can be other reasons like:

Multicultural individuals commonly think, perceive, behave, and respond to global workplace issues in more complex ways than monocultural individuals.

• Monocultural: Identity with one cultural group
• Slightly multicultural: Identity primarily with one culture, and to a lesser extent with another culture
• Moderately multicultural: Identity strongly with more than one culture
• Highly multicultural: Identity with more than...

Multiculturalism within individuals can be defined as the degree to which they know, identify with, and internalize multiple cultures.