When I was eleven or twelve years old my parents enrolled me in a summer camp in upstate New York. One of the regularly scheduled activities was sitting around the evening campfire learning new songs. I loved the words and melodies and sang them often (mostly to myself), even during the weeks and months after camp ended. One song particularly fascinated me--it was “I’m My Own Grandpa,” a fifties’ hit popularized by the great Guy Lombardo. The song tracks the hilarious series of paradoxical relationships that begin when the step-daughter of a newly married young man marries her new father’s father—making him his son’s son-in-law and the daughter (his wife) his son’s mother (as well as his daughter). Five verses and ten genetic calculations later, he realizes--with shock and horror--that “as husband of my grandmother, I am my own grandpa.” Hence, the title of the song.
That little song is more relevant today than it ever was in the fifties. New medical technologies, adoption policies and (re)marriage practices are rapidly changing the faces of families. Ordinary parent-child and brother-sister relationships have become extraordinary and difficult to define. Some mothers are bearing artificially conceived babies who may be related to both parents, one parent or neither parent. Who is the father, and is there more than one? Transplanting an identical twin’s healthy testis (or ovary) into his (or her) infertile co-twin has allowed these siblings to successfully conceive. But are the aunts and uncles of these children still aunts and uncles, or are they mothers and fathers? China’s One-Child Policy led to the abandonment and adoption of thousands of female babies, including twins. Young twins adopted by different families acquire different sets of relatives, so that one twin’s sibling is not her co-twin’s sibling. But what is she? Rare identical twin pairs include one twin who underwent sex reassignment surgery. Are these twins still twins and, if so, are they still identical? Possible human reproductive cloning may offer couples a child-bearing option that would produce children genetically identical to one parent. These parents and children are not twins, but what are they?
Here are my responses to some of the questions posed above; I imagine that some people will have a variety of views on these topics.
1. In my recent book, INDIVISIBLE BY TWO, I described the case of identical twins, Marcy and Tracy. Tracy was unable to conceive, so Marcy delivered two daughters for her sister. She did so by becoming pregnant via artificial insemination using her brother-in-law’s (Tracy’s husband) sperm. The twins were genetically the same, so that the children were as closely related to Tracy as if she had conceived them naturally. A DNA test could not distinguish the mother from the aunt—but Tracy was clearly the mother in this case as she raised the children from birth.
2. I discovered a fascinating case of identical male twins, one of whom was infertile due to anorchia, the absence of testes as birth. However, a testicle transplant from his identical twin enabled him to have children. The recipient twin was the biological father of his children as he was responsible for the conception--even though a DNA test could not distinguish the father from the uncle.
3. I am conducting a study of young Chinese twins, adopted separately as an indirect result of China’s One-Child Policy. This policy restricts child-bearing to one child in urban areas and to two children in rural areas. The society favors male children, so females are often abandoned, leading to separation and foreign adoption of some twin pairs, mostly female. This situation generates an array of relationships for which we lack names. For example, if one twin has another sibling, this sibling becomes more like a cousin to the twin sister because they are not reared together. This situation is highly unusual because twins typically have the same siblings!
4. There are rare pairs of identical female twins, one of whom undergoes sex reassignment surgery, believing that they were born as the wrong sex. In my view, these twins are still twins. I have witnessed wonderfully warm and supportive relationships between a number of such sets. I also work with twins whose twin have passed away, and continue to regard these “twinless twins” as twins. Being born a twin is central to one’s identity.
5. Human reproductive cloning became a possibility with the 1996 birth of Dolly, the cloned lamb. Many people have speculated as to the nature and consequences of relationships between adults who might raise cloned children. It is indeed unfortunate that references to such individuals have included terms such as “genetic twin” or “delayed twin.” In fact, they would not be twins at all! Elsewhere, I have set forth some criteria for what constitutes twinship. The main features include being conceived at the same time, being gestated in the same intrauterine environment, being born at the same time and being a member of a common cohort. None of these features would apply to cloned parents and children; thus, they cannot be twins.
I will end with a curious story of an older twin who contacted me over the Internet. It seems that his mother (who already had several children when he and his identical twin brother were born) was ill, so she decided to give one twin away for a while. This twin ended up being cared for by his aunt. The aunts also had a son, so the twin was raised with his cousin as though his cousin were a brother. The families met occasionally and when they did he had opportunities to send time with his identical twin—who now seemed more like a cousin!
It appears that whenever twins are involved, relationships take on a novel twist. At the same time, a scientific eye can discern important information from these unusual kinships.
For example, these separated twins were never studied, but based on published research, it is likely that the twins were more behaviorally alike than were the one twin and his biological cousin—despite the fact that they were raised apart. This underlines the fact that genes contribute to all phases of human behavioral development.
