I read an incredible novel several years ago about an English man who keeps a pair of boy-girl twins in his home and raises them with no spoken language to find out whether language is innate in human beings. It was terribly disturbing and well written, and I want to read it again but cannot remember the title or author's name. I vaguely remember the author's last name being some version of "Burns" or "Burnside" but all my Amazon and Google searches have been fruitless :(