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Not Your Child's Mom

Science's Story of Chimera

 by Wendy Stewart-Hamilton

I’ll admit that I am fascinated by the odd, the unusual and the downright weird.   I have often bought things simply because they were labeled “ugly” and have treasured them for their unique beauty.  I truly believe that the Potter’s hand does not slip.  

However, when the term Chimera entered my vocabulary, I can’t say that I was prepared for it and the subsequent outpouring of ideas and thoughts.  

In the documentary “I’m My Own Twin” on TLC (The Learning Channel www.tlc.com), I heard the word and learned of people who were indeed their own twin.  

The story begins with Moms.  Two very normal-looking moms, in fact, who discovered through different processes – one in needing a kidney transplant and the other having completed DNA tests on her children- that they were by scientific declarations, not their child’s mother.  Can you imagine the shock and the emotions that come with being told the most astonishing news, “You are not your child’s mother”? 

Now, this is something we typically hear associated with fathers, but not with mothers.    

Of course both the women knew differently, they had carried and delivered these children – they knew these kids were theirs.  

They were right.  In a fascinating quirk of Science and genetics, these mothers, and potentially many other people, have a condition called Natural Chimerism.   

Natural Chimera in this case happens when two separate (or fraternal) sets of twins unite into one embryo early on in the pregnancy.  This is two sets of egg/sperm and egg/sperm uniting to create one tetragametic Chimera.¹

Because these Chimeras have TWO unique types of DNA in their bodies, they can potentially, for example, have a kidney that is one type of DNA, ovaries that contain another type of DNA, and their blood may have a different type than their ovaries and so on.  

Yes, this is a little bit confusing, because we were taught in simple genetics that each of us are made up of our Mother’s DNA and our Father’s DNA and together they form our unique DNA, exclusive down to 99.9 percent as being ours.  Evidence of DNA is infallible, right? 

This might not be the case, and Chimera is more common than we think.  In fact, although only 30 cases of Natural Chimerism have been documented, it is likely that there are many more that have not been detected.

Chimerism is nothing new.  

In blood typing, where we are determined to be either a positive or negative of A, B, O or AB, something we are not normally informed of is that many persons indeed have a form of Chimera.²   In fact, “Human chimeras were first discovered with the advent of blood typing when it was found that some people had more than one blood type. Most of them proved to be "blood chimeras" -- non-identical twins who shared a blood supply in the uterus. Those who were not twins are thought to have blood cells from a twin that died early in gestation. Twin embryos often share a blood supply in the placenta, allowing blood stem cells to pass from one and settle in the bone marrow of the other. About 8% of non-identical twin pairs are chimeras.”¹ 

Persons who have received a blood transfusion, organ donation or transplant, received immunizations, flu shots or allergy shots, or have even given birth to a child may or have been party to the process of blood Chimerism, and are indeed in one form or another, a Chimera.  

During pregnancy, the majority of mothers and children will exchange cellular information in a process called microchimerism.  This is actually beneficial to the Mother and Child at this point because it encourages the mother to not treat her child has a foreign body and spontaneous abort or miscarry her child.   However, the cells and information received from the child remain.  In fact, in some studies it has been shown to remain decades after childbirth in a mother’s system.   When a mom has other children, it is highly likely that the DNA information from the other child is passed onto the younger sibling in the womb creating Chimeras, or individuals who have been affected by Chimerism.  

In recent years, more information regarding Chimeras has been brought to light because of genetic cloning, stem cell research and in vitro fertilization, all of which are done through processes of Chimerism, with varying results.  

Even as I sit and write this article, knowing that I have studied for the last six hours specifically on Chimera, this subject and its implications remains mind-boggling and produces many complex questions with profound scientific, moral and religious implications.    

What is truly NATURE and what is nurture? 

How does this new information combat the idea that DNA tests are basically infallible? 

Could a Dad get a false negative as being a child’s father simply because he is a Natural Chimera? 

  Even more frightening, could rapists get away with rape because their blood has a different DNA type than their semen or other body fluids?

Could crimes go unsolved because potential suspects are excluded because of two types of DNA being at the scene, if it there is only ONE person, a natural or tetragamic Chimera, involved? 

How does Chimerism come into play regarding the topic of homosexuality?

These are all questions that probably won’t be answered any time soon by Science or Philosophy, but are well worth the brain power it takes to ask them.

If interested or intrigued, the show “I Am My Own Twin” is showing again on TLC on 10/6 @ 10:00 PM(EST) and 10/7 @ 2:00 AM(EST).  

Sources: 

1. http://en.wikipedia.org/wiki/Chimera_(animal)#Natural_chimerism
2. http://www.medterms.com/script/main/art.asp?articlekey=8905

 More information on Chimera:  

http://www.answers.com/topic/chimera

http://arbl.cvmbs.colostate.edu/hbooks/genetics/medgen/chromo/mosaics.html

http://news.bbc.co.uk/2/hi/health/3264467.stm

http://www.bellaonline.com/articles/art32872.asp

http://mypage.direct.ca/c/csamson/multiples/1formed.html

http://www.theage.com.au/articles/2003/11/27/1069825920727.html

 Please note that these sites are provided for informational purposes only.  No support or implied endorsement of the content of these sites should be considered as being made by Inspired Moms and the staff or members thereof.