Pedigrees are paragons of infographics — “graphic visual representations of information, data, or knowledge intended to present information quickly and clearly.” Yup, that’s pretty much what a pedigree is. Just think of how much clinical and genetic information you can glean from scanning a pedigree for even just a few moments. Eliciting a pedigree during a counseling session is also a great way to establish rapport and trust with a patient, get a grasp on family dynamics, and gain insight into patients’ understanding of disease etiology (“I’m not very close with my father. He left when I was pretty young. I think he had leukemia but he worked in a shipyard and was exposed to all kinds of chemicals.”). The family story is often more interesting than the family history. Then there’s that appealingly simple geometry of squares/circles/diamonds/lines and the satisfying symmetry of the paternal lineage on the left and the maternal lineage on the right. Nice, neat, clinically objective, non-judgmental, and harmless, right?
Well, maybe not always so harmless and objective. Symbols can be imbued with power by the information they communicate and that power can be used to control, harm, and manipulate people and reinforce social power structures.
As I’ve written about before in this space before, pedigree nomenclature and structure reflect what Judaeo-Christian Westernized cultural values consider to be an “ideal family.” Standard pedigree structure works best for a single mating between a man and a woman, along with their respective offspring and antecedent and descendant generations. Maybe you can squeeze in a second mating for one or two individuals in the family, but after that, things get pretty messy and difficult to read.
Over the last century or so, cousin marriages have been discouraged in most Westernized countries and in some cases are illegal. Although pedigrees can incorporate an occasional consanguineous mating without becoming too unwieldy, the picture gets complicated if there are multiple inbreeding loops like those found in the many societies where cousin marriage is the norm. And as far as sex and gender go, you have two choices — square or circle, man or woman — that are dictated by an assessment of your genitalia (this will change with the latest iteration of pedigree nomenclature; see below).
The implicit cultural messages here are that you should have one life-long unrelated mate and that you are either a man or a woman, no allowances made for people who identify otherwise.
The oppressive potential of pedigrees is illustrated in the pedigrees collected by the Eugenics Record Office, which operated out of Cold Spring Harbor on New York’s Long Island in the first few decades of the 20th century. Look at the trait key used to classify people in a pedigree and it evokes a smile, an eye roll, tears, a grimace, a forehead slap, or all of the above. Sexually immoral. Criminalistic. Wanderer. Neurotic (for those of you who like language trivia, the pointing finger symbol that is used to indicate a proband is called a manicule or, more informally, a bishop’s finger).
But these labels and symbols are not just harmless historical curiosities that were the products of a few warped minds. This was the era of mandatory sterilization laws in the US and elsewhere. If one of those symbols represented you, the state had the legal right to perform surgery on you against your will to prevent you from having any(more) children. Three generations of imbeciles are enough already, and that ruling was by a liberal Supreme Court that included Louis Brandeis in the majority opinion.
In contrast to how “dysgenic” families were portrayed, pedigrees could manipulate the viewer in the other direction by omitting information of eugenically desirable families. The Darwin Family pedigree below was, for all intents and purposes, the logo of The Eugenics Education Society, headquartered in London and whose president at the time was Leonard Darwin, one of Charles Darwin’s sons. Note that virtually all of the males in the family are “Brilliant” or had “Scientific Ability” but none of the women apparently possessed these traits. More subtly, many of the dysgenic traits described in eugenically undesirable families were omitted from the Darwin pedigree – opium addiction, deafness, intellectual disabilities (Darwin’s much beloved last child, Charles Waring Darwin, likely had Down syndrome), seizures, and alcoholism. Indeed, Darwin himself was so concerned about his family history that he wrote a letter to his father asking for his advice before starting a family (Darwin’s father wrote a similar letter to his father too).
A stark illustration of the power of symbols came up in discussions about updating pedigree nomenclature among the NSGC Pedigree Standardization Task Force, of which I am a member. One of our recommendations is a gender-first nomenclature, that is, a person’s self-identified gender should dictate the symbol’s shape, not their sex assigned at birth. We also considered symbols to use for people who do not identify as either male or female. In reviewing the literature and eliciting suggestions from the genetics and other communities, some suggested using an inverted triangle for someone whose gender identity is nonbinary. However, we rejected that suggestion in favor of a diamond shape because inverted triangle badges were used in Nazi concentration camps to distinguish among the various types of prisoners, such as political prisoners, criminals, prisoner of war, “gentiles who assisted Jews,” Roma, mentally ill, or Jews (the Magen David is essentially, two triangles). The triangle that defined you could mean the difference between life and death.
The potential harm of pedigree symbols looms large today now that states have taken to passing laws that criminalize abortion. Suppose that you are practicing in a state like Louisiana after a strict anti-abortion law is passed and you are taking a family history from a someone who had a pregnancy in which anencephaly was diagnosed and she managed to obtain a pregnancy termination through an underground network. If you document that pregnancy with the annotation VTOP (voluntary termination of pregnancy) below, you could potentially open her up to legal prosecution.
A similar outcome could arise in a states like Texas or Alabama that have banned gender-affirming treatment for children, legislation that, as far as I can tell, is often motivated by cynical politics and hate-driven willful ignorance. If you practice in these states and are consulting with a parent who has a child who identifies as female but was assigned male at birth and has undergone gender-affirming treatment such as puberty blockers, you would – under the new guidelines – depict this in the pedigree with a diamond, the annotation AMAB (Assigned Male at Birth), and perhaps further annotations about what treatment was provided. If that pedigree fell into the wrong hands, the parents and the treating physician could be charged with child abuse. And, by law, you may be required to report it to the state, just as health professionals are usually required to report any type of child abuse.
A genetic counselor could be put in the position of either falsifying the medical record or omitting clinically critical information. Talk about a rock and a hard place.
In the idyllic past, we mostly worried about insurance companies getting their hands on pedigrees. Now we have to worry about the prosecutorial system accessing them. Absolutely nothing good will come of that. It’s possible that the judicial system may block or limit some of these laws, but I am not too hopeful at the moment.
Nothing in science and medicine is value-neutral. Everything we utilize and do in our clinical practice can be used for good and for bad and we often have no control over how it is used and abused. Nor should we lose sight of the fact that one day future genetic counselors will look at our pedigrees and other practices and pass critical judgment on us. We should strive for ethical humility amidst our righteousness.
As an added bonus for that small circle of practitioners who love pedigrees as much as I do – fellow PedHeads – you might be interested in this article I wrote long ago in a genetic galaxy far away about the history of the pedigree in genetics.