Separated Twins and What They Teach Us

The current issue of Newsweek as a really fascinating story about two families who adopted girls from China.  It turned out the girls were twins.   It’s another variation of the separated at birth story, and as always, it’s gives me a lot to think about. 

Meredith Grace Rittenhouse and Meredith Ellen Harrington were adopted into different American families who just happened to give both girls the same first name.   They had arrived at the orphanage in China at different times and no on knew they were related. They are not identical twins, which are apparently more accurately called monozygotic twins, but rather fraternal twins.

That their families found each other when the girls were four was essentially serendipitous.  But serendipity or no, they did find each other.   The girls are now nearing 10 and it’s clear that they are deeply tied to one another. 

Interestingly, the girls have become part of a study of an ongoing study of twins.   While twins separated at birth are rare enough, it’s even more unusual that the separated twins find each other while they are still young. Yet this has happened before with children–girls–adopted from China.   And so Nancy Segal from Cal State Fullerton is conducting an ongoing study of ten sets of separated and then reunited twins and 30 sets of twins who were adopted together.   It’s fascinating to think of what we might learn from this study when it is completed.  

One obvious point of the article (and presumably the study) is that genetics matter.   At the same time, the girls are bonded to their adoptive parents.    It’s not clear what the ultimate implications of all this are, but that they are complicated is not lost on the people involved.   One of the mothers is quoted as saying:   

“We have always felt that family bonds are not dependent upon genetic connection. It is the foundational belief of our family,” Leigh Anne [Harrington], a family therapist specializing in international adoption issues, wrote in an e-mail to a friend right after the Merediths met. “However, there is no denying that these girls share something beyond. It is amazing

But I think there is more than just genetics to think about.   As I understand it (and I’m happy to be corrected as I profess no real expertise) fraternal twins are no more closely related than are any siblings.   They arise from two separate eggs fertilized by two separate sperm, which would be the case with any siblings.  

(By contrast, the article explains that monozygotic twins arise from a single egg/sperm that then divides and so there is much more genetic commonality, although it is wrong to say that they are identical.  Monozygotic twins do not have identical DNA.  This actually addresses a question I’d been wondering about, so I’m happy to know it.)

Anyway, I think the article suggests pretty clearly that there is a special bond between twins who are reunited.  While it doesn’t say so explicitly, I take the implication to be that this is a greater and/or more immediate bond than exists between non-twin siblings.   (After all, much is made of the fact that the children are twins.)   If that is the case (and I stress if, for perhaps I am making an unfounded assumption) then while genetics offers some explanation, it does not completely explain the phenomenon.   After all, from a purely genetic point of view, siblings and fraternal twins are indistinguishable.  

What distinguishes twins from siblings  is the twins shared gestation.   And so that’s what this article leaves me wondering:  is that experience–of having shared a womb–part of what creates the bonds between these girls?   I think that would have interesting implications.   I wonder if this is part of what Nancy Segal is studying?


6 responses to “Separated Twins and What They Teach Us

  1. It is true that monzygotic twins don’t have identical DNA. There are small differences in epigenetic changes in their genomes(caused by the environment) and in copy number variation. There is no practical DNA test currently available which can detect these differences, so for all legal purposes their DNA is identical. Such tests will probably be available within a few decades.

  2. Monozygotic twins are identical DNA wise. Epgenetic factors neverchange the DNA just its expression.

  3. True, but copy number variation (missing segments, muliple copies and flipped orientation) does.

  4. Sharing the womb also means sharing both genetic parents (except for the rare incidence of bipaternal twins). Dizygotic twins can be almost certain of sharing 50% of their genome. For other siblings there is a small chance that they have different fathers and therefore only share 25% of their genome. Even if the difference is statistically very small, it is difficult to dismiss entirely that it could have an effect in making twins bond even stronger with each other than ordinary siblings.

  5. how this relates to the status of surrogacy- I’ve come to the conclusion that gestation and birth is of significance- spending 9 months as part of the same body can’t be overlooked and the surrogate should have some parental rights.
    However, I would still give greater weight to the genetic parent as the influence of gestation is negligible compared to the influence of the genes.

    • Kisarita wrote:
      “I would still give greater weight to the genetic parent as the influence of gestation is negligible compared to the influence of the genes.”

      I absolutely agree! It is the gene connection that is related to the meaningful genetic familial ties and ancestry of the child. BUT to admit that importance – above the importance of the gestation vehicle (legally) would weaken these arguments that biological father’s and mother’s can be so easily cast aside as only sperm and egg vessels – and that intention and bonding are the only valid parenting and responsibility prerequisites.

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