What was unusual about the study was an intentional separation of identical twins for the purpose of research. The purpose was to understand the impact of nature versus nurture, heredity versus the environment.
I was getting my master’s degree in clinical social work at Columbia University, and I was placed with an adoption agency doing home studies, working with the young women who were giving up their babies. We were also monitoring the success of the adoption by visiting the newly adoptive parents' homes. Although I was not directly involved in Neubaur’s study, he often talked about it with me. I remember some of the examples of the research. There were originally 21 children (three of them identical triplets). They were given up for adoption and separated at birth. None of the parents knew of the other twin’s existence.
Studies of twins separated at birth and reunited exist, but this is the only study that followed the infants from birth. The parents were told it was a development study. A team of psychiatrists, pediatricians and observers documented information through psychological tests, school records, parental interviews, films and minutes of nearly 1,000 weekly conferences.
Several children found each other through friends who knew one twin and recognized the uncanny similarity upon chancing on the other twin at some other location. Of the final 13 children involved in the study, three sets of twins and one set of triplets have discovered their siblings. There are still four people who don’t know they have an identical twin.
The biggest surprise from this research was that twins reared apart did not exhibit any more differences that those reared together. One reconnected set of twin girls found to their amazement that even though they had been raised a continent apart, they had the same favorite book, the same favorite music.
I have gathered a few highlights of the study that point toward the prevalence of DNA over preferences in behavior and life choices:
1. Both twins had a diaper rash within a day of each other. One pediatrician suggested changing the milk formula and the other suggested a different laundry soap, both babies got better at the same time.
2. One mother complained of her child’s poor eating habits — he would not eat unless there was ketchup on his food. When queried about the food habits of the other twin, that child’s mother kept saying there was no problem. When the researcher kept probing, she finally said all was well as long as she put ketchup on all his food.
3. One little girl was very involved with ice skating and spent a lot of time in the rink. Her twin loved roller skating and did it as often as she could.
4. Each twin had an abscess in the same tooth a couple of days apart.
5. Two of the infants were placed in homes with very different mothers. One was an insecure, often neglectful mother, who was often neglectful, while the other was a confident, doting mother. Surprisingly, both girls exhibited similar behaviors such as thumb sucking, nail biting, clinging to their blankets, wetting the bed until they were 4 and crying when left alone. They were both prone to nightmares and full of fears.
6. There is an interesting example of a young boy in his late teens repeatedly getting into trouble with the law. He ended up in jail, while, at the same age, his twin joined a religious sect, shaved his head and walked about in an orange robe begging on streetcorners. Although the specific behaviors were different, each chose an alternate lifestyle very much at odds with the mainstream.
This study was never published to protect the identities of the remaining twins. It is in the Yale University archives, not to be published until 2066. This study could not be replicated today. At the time, it felt like an opportunity for research to resolve the "nature versus nurture" controversy, and no harm was thought could come from separating the twins. In 1981, the state of New York began requiring adoption agencies to keep siblings together.