Blue-eyed girl

The early days

I’m not sure I would be in the field of genetics if I didn’t have blue eyes. I remember my first introduction to genetics, in my 7th grade “life sciences” class, which is just biology for middle schoolers. We were learning about Mendel, his peas, and the laws of genetic inheritance. One way to depict the transmission of genes and traits from parents to offspring is with a Punnett Square.

Punnett Square
Punnett Square. Source: Wikimedia

In its simplest form, the square illustrates how the form of one gene in the parents, call the two forms “A” and “a,” can be passed on to an offspring. Let’s just say “kid,” lest we sound like cold, hard scientists. Different forms of the gene, or genotypes, in the parents lead to different expected proportions of genotypes in the kids. If both parents are Aa, then you’d expect 25% of the kids to be AA, 50% to be Aa, and 25% to be aa. This is because each parent only passes one of their forms to the offspring: the father gives one copy in the sperm and the mother gives one copy in the egg. Each time an egg or sperm goes down the chute, it has an equal chance of being either of the parent’s two forms, meaning each kid has the same chance of being either AA, Aa, or aa.

Don’t get hung up on the AA/Aa/aa stuff, especially since that can be a really non-intuitive way to think of genes (the DNA molecule is made of 4 chemicals nicknamed A, C, T, and G – all uppercase). More important for this story is that my teacher drew a Punnet Square for the trait of eye color. Eye color is used all the time to demonstrate genetic principles, which is ironic given that it’s actually a very complex trait and not well-understood. (If you want to pass yourself off as a human genetics scientist, just say something like “we’re still trying to elucidate the genetic architecture of eye color,” and they’ll let you into all the parties, journals, grants, etc.) But in the toy example, “A” represents a form of the eye color gene for brown eyes and “a” for blue. Aa individuals might either have a blended form, such as hazel, or just have a really loud A form that drowns out the blue “a” form, resulting in brown eyes.

I have blue eyes, so what I saw in that little quadrant of the Punnet Square up on the chalkboard was an opportunity for uniqueness, for exclusivity. I am the youngest in a family of three daughters, my first name was arguably the most popular of all girls born in 1983, I have brown hair and grew up middle class in suburban East Tennessee. Granted many people have blue eyes, but no one in my immediate family. Granny (my paternal grandmother) did. My mom has brown, my dad has hazel, and both my sisters have brown. So let’s remember that eye color is not as simple as one gene with two forms A and a, but something happened in the making of me that caused a previously hidden blue eyed “gene” in my mom to combine with my dad’s partially observable blue eyed “gene,” such that I have 100% blue eyes. Step aside loud brown A genes, and let that “aa” shine.


So fast forward almost two decades. Now I’m in something like 21st grade and pursuing a PhD in Public Health Genetics, an interdisciplinary field that studies the science of genetics, but also the ethical, legal, and social implications (“ELSI”, pronounced else-ee) of using genetic information – in research, in health care, and in everyday life. My research is particularly concerned with that latter piece, the “everyday life” part.  Many people, not just blue eyed 7th graders, have noted that genetics (DNA, genes, genomes) has a captivating mystique. DNA is generally hidden to us yet integral to our existence and function as living beings. It is part of who we are, where we came from, and to some extent where we are going.* The first time we knew the full sequence of the human genome was in ~2001, after over 10 years and $3 billion devoted to the Human Genome Project (alongside some private ventures). The cost of sequencing has fallen so hard and so fast that sequencing whole genomes is becoming an increasingly common part of research and, in some currently limited ways, in medical practice. But for most people, at least our own genome still remains hidden to us, though we carry it around with us all the time.

*I do not endorse these “isms”

Above I wrote that DNA is “part of who we are, where we came from, and to some extent where we are going.” A quick but important aside to emphasize “part of” and “to some extent” in that sentence and to clarify what I am not saying about genetics. I don’t think genetics is a crystal ball or sacred text or panacea for all our personal and communal ills on this planet. Many of the societal and health related problems we face as a nation and as a planet have very little to do with genetics. In fact, efforts to understand genetics can often detract (attention, funding, etc.) from more pressing needs and problems. Social inequalities in health and access to health care are traceable to assaults much bigger and much further upstream than genetics. Basically, genetics isn’t deterministic in the sense that having certain DNA sequences translates 100% of the time into certain outcomes. Rather, there is a complex web of ecosystems, communities, families, and individuals that all interact to yield certain social and health outcomes.  So genetic determinism is not something I subscribe to or espouse.

Another “ism” I do not intend to promote with my comments here is “genetic essentialism”, or the idea that we can be reduced down to, or “essentialized” as our genetic make-up. We are way more complicated than that (maybe this is a good time to check your Facebook news feed and confirm that last statement).

Open Reading Frame

I’ll talk more about what I think about genetics and what I’m doing in my PhD research in future posts. I’m still working out what the right blog frequency is, both for me and for you, my esteemed reader. But my initial thought is to post at least every week or two. Sign up to get notified of new posts via RSS feed or stuff like Digg Reader and then you’ll automatically receive your next dose.

Ps – Thanks to Ms. DeRoos, my 7th grade life sciences teacher, for teaching me about Punnett Squares, albeit through the intuitive but slightly misleading example of eye color.

3 thoughts on “Blue-eyed girl

  1. This is awesome, Sarah! I hope plenty of people read this and their fears of a world governed by the circumstances of GATTACA are assuaged! I’m looking forward to reading more.

    1. Thanks, Emily! Ah, GATTACA — now that is an example of genetic determinism!! It’s funny how much this movie comes up in discussions of ethical and social implications of genetics, even almost 20 years after it came out.

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