Wednesday, August 28, 2013

Biology - part one

I follow a handful of embryo adoption blogs and know that there are a variety of things that the donating couple could be called without incurring much debate:  genetic parents, donating couple, donors...  With embryo adoption, unlike the other traditional forms of adoption, the genetic parents are not the birth parents.  The adoptive parents are the birth parents and that's so cut and dried that there's no grounds for debate on that terminology.

And then you get to the word "biological".  Que discussion.

Option A:  "Biological" can be used interchangeably with "genetic".

Example:  Cora and Mac are not my biological children.  They do not share my genes, my DNA.

Option B:  Biological is tied in with the gestational experience and birth.

Example:  Cora and Mac are my biological children; we shared the biological experience of gestation and birth.  They are who they are today in part because of how my body grew them.

The distinction is not quite as clear cut as one may believe due to a concept called "epigenetics".  Essentially, the woman who carries the pregnancy is more than just a vessel.  In the somewhat recent history of scientific discoveries, researchers have discovered that there are connections formed between the child(ren) in utero and the mother, beyond the inherited DNA.  Everything put into the pregnant woman's body influences the development of the embryos.

I know that we adopted embryos, but I've found clearer wording from egg donation sources.  The following quote is still relevant because in both scenarios, material is introduced in to a woman's body that is genetically foreign. 

Freedom Pharmacy has a booklet about egg donation (p. 10):

“Perhaps the greatest myth surrounds pregnancy. Many believe the uterus is simply an incubator. Nothing could be further from the truth. The most important aspect of all pregnancies- including egg donation pregnancies- is that as the fetus grows, every cell in the developing body is built out of the pregnant mother’s body. Tissue from her uterine lining will contribute to the formation of the placenta, which will link her and her child. The fetus will use her body’s protein, then she will replace it. The fetus uses her sugars, calcium, nitrates, and fluids, and she will replace them. So, if you think of your dream child as your dream house, the genes provide merely a basic blueprint, the biological mother takes care of all the materials and construction, from the foundation right on up to the light fixtures. So, although her husband’s aunt Sara or the donor’s grandfather may have genetically programmed the shape of the new baby’s earlobe, the earlobe itself is the pregnant woman’s “flesh and blood.” That means the earlobe, along with the baby herself, grew from the recipient’s body. That is why she is the child’s biological mother. That is why this child is her biological child.”

Another source elaborates further on the impact of epigenetics and well, egg donation, but, as I said earlier, it's relevant in the discussion of embryo adoption too.

"Genes must be ‘expressed’ within an individual in order to have an effect.

"The same gene or genes can express in a number of different ways depending upon the environment. A gene can remain ’silent’ or unexpressed; it can be expressed strongly; it can be expressed weakly, and so on. There is also an entire field of study called imprinting having to do with which gene you ‘activate,’ the copy you received from your mother, or the copy you received from your father.

"The field of epigenetics studies these phenomenon, and popular journalism is just starting to write about it. While the Human Genome Project was still underway, we usually heard genes referred to as ‘the Bible’ of the human being, as a kind of absolute truth concerning the fundamental nature of the

"That is now changing.

"In a donor egg pregnancy, the pregnant woman’s womb is the environment.It is her genes, not the donor’s, that determine the expression of thedonor-egg baby’s genes.

"A donor egg baby gets her genes from the donor; she gets the‘instructions’ on the expression of those genes from the woman who carries her to term.

"This means that a donor egg baby has 3 biological parents: a father, the egg donor, and the woman who carries the pregnancy.

"The child who is born would have been a physically & no doubt emotionally different person if carried by his genetic mother.

"In horse breeding for example, it’s not uncommon to implant a pony embryo into the womb of a horse.  The foals that result, are different from normal ponies.They’re bigger. These animals’ genotype – their genes – are the same as a pony’s, but their phenotype – what their genes actually look like in the living animal – is different."

I kind of have mixed feelings about all of this but am struggling to put my thoughts into words.  So, for now I'll ask, what do you think?

1 comment:

  1. This whole area of epigenetics is fascinating stuff. Love thinking about it. Genes are like the backbone or blueprint, and our environment is what gives those genes their expression. No one has ever thought twice about how a prenatal environment can negatively affect the unborn in ways such as --- smoking, drug use, malnutrition - but these are always viewed as developmental defects--- just the tissues and the organs. But it only stands to reason that this affects nature in positive and neutral ways as well -- the molecules that tell the code to express or not express the "blueprint" traits. We know that even with a genetic family history of diabetes or cancer we can alter our destiny with diet and exercise and behavior changes. This is just one more example of how the environment affects our genetic selves.