why i never believed deborah tannen

She says, in http://roomfordebate.blogs.nytimes.com/2010/04/12/why-do-educated-people-use-bad-words/:

People who speak more than one language report that they always curse in their native tongue; they can say swear words in a second language but they don’t feel them — the gut link to emotions just isn’t there.

This is emphatically not true. Cursing, in my experience, is one of the easiest things to change. My father curses only in English (although he'll say it's only because he never cursed in Tamil). Lots of people curse in the language they happen to be speaking. Incidentally, Birbal was wrong about this too.