According to Wikipedia, at least in the past, Mandarin is the number one native language of all people. Furthermore, and more offensive to Americans, the number one country for most native English users is listed as India, not the United States. Apparently Indian Wikipedians (probably with the consent of the many anti-American Wikipedians who frequent that site) have difficulties with the term native. A native language is not a secondary language, and all native users of English should be fluent in it (not only use a few catch phrases here and there).
I don't know about Acts 15:20, but my wife and I have been vegetarians for years. How can your learn mercy when your mouth is filled with blood?