Double Deaning: Reflections in a Mirror

Nearly everyone finds twins interesting. That is so, in part, because twins are relatively rare, with only three or four out of 1,000 births producing twins and only about 25 percent of those being monozygotic—the technical term for “identical twins.” Even rarer are those identical twins who are known as “mirror twins”—those who have opposite physical characteristics. Since the zygote has split a week or so after conception into two facing halves, it is logical to find that some identical twins have this “mirror” characteristic. One of the pair may be left-handed and the other right-handed; it may even be that one is myopic in one eye while the other is myopic in the other eye. There is anecdotal evidence—and much fascination—with accounts of mental telepathy between identical twins and even such nongenetic factors as independently in later life deciding to buy an automobile of the same brand, model, and color!