Dr. Oliver Sacks, the famous neurologist and author, passed away in summer 2016. One of my favorite essays from his volume The Man Who Mistook His Wife for a Hat (1985), is “The Twins.” John and Michael were twenty-six-year-old autistic savants who showed unusual memory skills and number manipulation, both of which brought them deep satisfaction. Sadly, their physicians separated them in 1977 to prevent what they saw as the unfavorable communication with one another. This unfortunate decision cost was made at the expense of their exceptional talents and happiness.

Sacks was interested in many forms of atypical human behavior, one being selective mutism (SM). SM is a social anxiety disorder characterized by failure to speak in some situations despite normal verbal behavior in others. Typically, it is diagnosed when children enter a new setting, affecting approximately .1% of school children, mostly female. A familial component underlying a predisposition to this disorder has been suggested.   

In 1986 Sacks published a review of Marjorie Wallace’s book, The Silent Twins (Wallace, 1986) for the New York Times (Sacks, 1986). The identical twins in question, June and Jennifer Gibbons, were born in 1963 and were of West Indian descent. They were raised on an army base in Haverfordwest, Wales with several elder siblings. The twins were inseparable and uncommunicative, eventually entering a life of fantasy and crime, and placement in Britain’s Broadmoor psychiatric facility, in 1982.

Sacks’s review opens with a historical summary of twin research; however, it contained an incorrect statement: “Through the study of twins—especially identical twins, early separated and separately reared—it would be possible, Galton wrote, to ‘weigh in just scales the relative effects of Nature and Nurture, and to ascertain their relative shares in framing the disposition and intellectual ability of men” (p. 3). Galton was not the first to recognize the research significance of reared-apart twins. In fact, the first investigator to publish a paper about reared-apart twins was Paul Popenoe, in 1922. In fact, Professor Thomas J. Bouchard, Jr. and I determined that the first mention of reared-apart twins occurred in the play Menaechmi, (The Twin Brothers), by the Roman comic dramatist Plautus, who lived from 254-184 B.C.

I noted this error in a letter that I sent to the New York Times; the letter was not published, but it was forwarded to Dr. Sacks. My letter and his reply are reproduced below. Given the continued attention to Oliver Sacks’s work during his life time and in the time since his death, I wanted to share these materials with readers everywhere. A longer version of this essay and the actual documents (my letter and Sack's reply)  are available in Segal, N.L. (2017). Oliver Sacks: Our correspondence about twins. Twin Research and Human Genetics, 20(4), 363-369.

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