Different cultures talk about different things in their everyday lives. Native speakers very aware of what they should and should not talk about with specific categories of people in their own language, but rules may be different in a foreign language. Both teachers and students need to develop a sense of “taboo” subjects. If they are to avoid offence. Good conversationalists use stress and intonation to keep conversations going. A fall on words like “O.K.” or “So”, often serves to show that we are about to change the subject.
Patsy M. Zightbown and N.Spada. 2006. How language is learned. Oxford University Press.