The most expectable answer is socialization.
This term is used to describe the process in which people learn the values, norms, and beliefs of a particular society/culture.
Therefore, for this indian couple, their early and previously-arranged marriage is nothing unusual because they were taught that's the most common thing for (indian) people to do. And you, well, you were taught differently; probably: that is better to wait until you grow old enough, and are sufficiently independent, to support a household. So, you get a "cultural shock" by hearing about how this couple got married.
