Twin research - new article on the wombtwin survivors site

Twins are unusual. They are interesting because they are so rare. They have always been a favourite subject of myths, folk tales and drama. Identical twins in particular are objects of great fascination and their similarity has caused us to ponder the deepest questions about the nature of human identity. (1) Few people are indifferent to witnessing the birth of twins. The womb, which is clearly designed to carry one baby, manages to carries two, and they are both born alive. Of course the twins we see are always in pairs. They are often, if not always, together. They seem to be bonded by a connection that goes back to their time together in the womb. A lone twin is a sad sight, for in the public eye this person surely is no longer a twin, because twins come in twos, we all know that.


A short history of twins

The scientific study of twins and twinning, as far as we know, is relatively recent when compared to other branches of obstetrics. One of the first publications to consider in detail the biological nature of twinning in humans was published in 1883.(2) It was written by Francis Galton, who was one of those remarkable nineteenth century English thinkers who laid the basis for almost all the later theories on twinning - that is, until the development of ultrasound and artificial methods of reproduction a hundred years later. He gathered his material by “sending circulars of inquiry to persons who were either twins themselves or near relations of twins.” He wanted to discover if the obvious similarity between twins was due to “trifling accidental circumstances” or something much more profound and as yet unnoticed and un-remarked.

Galton was aware from animal studies that twins arise out of two very different events. One is where two or more are born, each developing from a separate ovum. The other is caused by the development of “two germinal spots” in the same ovum, each of which becomes baby. Galton noticed that if the ovum divides, the twins are wrapped in the same membrane – the chorion - and invariably of the same sex. He was puzzled that all twins were not alike, and that boy/girl twins in particular were never alike. He also noticed the phenomenon of the Alpa and Beta twin in many twin pairs but, lacking our modern vocabulary, he described them thus:

The one was the more vigorous, fearless, energetic; the other was gentle, clinging, and timid; or the one was more ardent, the other more calm and placid; or again, the one was the more independent, original, and selfcontained; the other the more generous, hasty, and vivacious. In short, the difference was that of intensity or energy in one or other of its protean forms; it did not extend more deeply into the structure of the characters. (3)


Galton was the first to name the Nature - Nurture debate as such, and saw that twins who were very alike in their youth “…continue their lives, keeping time like two watches, hardly to be thrown out of accord except by some physical jar.” It was clear to Galton and others at that time, following the publication in 1858 of Darwin’s Origin of Species, that these twins had similar genes. The science of genetics - and its dark twin eugenics - was developing rapidly......[more]