Ka mua ka muri (Walk backwards into the future with your eyes fixed on the past) – Maori whakatauki (proverb)
The NSGC Pedigree Standardization Task Force, of which I am a member, recently published updated guidelines for pedigrees, with a focus on sex and gender inclusivity.* Essentially, the guidelines state that the symbolic representation of individuals in a pedigree should be based on self-identified gender rather than sex assigned at birth. Squares, circles, and diamonds for people who identify as men, women, and non-binary people, respectively, supplemented by clarifying annotation when appropriate. A subtle implication of gender-focused pedigrees is that the internal logic of pedigree construction is no longer compatible with exclusively placing the “man’s family on the left and the woman’s family on the right” (to use the gendered language of yesteryear; more gender neutral but more awkward sounding terms might be sperm provider and egg provider). This point was illustrated in the article’s accompanying tables but not specifically called out in the text, though it is the subject of a brief follow-up Commentary. Of course, the discretion of which side of the pedigree to use for which side of the family is up to the individual counselor’s preference. It may take some getting used to, especially for those of us who have been drawing pedigrees for a very long time (“Oh no, how am I ever going to spot x-linked inheritance?”). But it’s a freeing choice rather than a restrictive mandate.
The reasons behind abandoning the long standing left/right tradition is straight forward. If pedigrees are based on gender, there are more than 2 genders, so a pedigree cannot logically and consistently be divided into halves. For example, if you are working with a couple in which one member was assigned male at birth but identifies as a woman and the other assigned female at birth but identifies as a man and has undergone gender-affirming surgery, which person goes on which side of the pedigree? Furthermore, gender identity may change over time and so placing an individual’s family lineage on the left or the right based on gender could result in the unnecessary and confusing re-drawing of pedigrees over time. Eliminating the left/right prescription also de-prioritizes males, who previously would be the first person encountered when “reading” a pedigree from left to right. Yes, I recognize that a pedigree can be read in many ways, not just left to right, and the proband arrow is the initial focal point that draws you into the image. But the standard reading frame in Western languages is left to right. And the pedigree’s generation/individual numbering system (I-1, I-2, II-2, etc.) is such that individual #1 in the pedigree (I-1) is usually the male founder of the paternal lineage.
Pedigrees and genealogies in one form or another go back well over a thousand years. During that time, while it has been by no means uniform and universal, the majority of pedigrees followed the paternal lineage left/maternal lineage right tradition. So how did this tradition arise (for clarity, I’m going to stick with the terms paternal and maternal to keep with the linguistic flavor of the times during which pedigrees have evolved)? One possibility, of course, is that it was a fifty/fifty kind of thing. When you divide the world up into two genders, one gender’s family will wind up on the left and one will wind up on the right and so it may have been that the paternal lineage just wound up on the left and the maternal lineage wound up on the right. But I think that a trip back through the history of pedigrees and other genealogical diagrams reveals the influence of the Western male gaze in establishing this tradition, along with eugenics, and, of all things, the Roman Catholic Church.
Let’s start this backwards journey in 1995, when the Pedigree Standardization Task Force published it’s original guidelines. Figure 2 in that article states “If possible, male partner should be to left of female partner on the relationship line.” Why did we make that recommendation? Because, well, that’s the way we were taught to draw pedigrees. It was a given; we didn’t think about it too much.
Go back about a century or so, and we see the role of eugenics in shaping pedigree format. In 1912, the Eugenics Record Office (ERO) published Bulletin No, 7, The Family History Book. Page 94 of that booklet contains a somewhat condescending critique of a pedigree of a “dysgenic” family, drawn by one the ERO’s primarily female Eugenic Field Workers, for the purposes of illustrating pedigree standards. The authors state “In this pedigree, the field worker has charted the males to the right and females to the left; this should be reversed for sake of uniformity of practice.” But they make no mention of where/why that practice arose. This same ERO publication recommended using the generation/individual Roman/Arabic numbering system for generations and individuals alluded to above.
Over in England, the male gaze was at work as well. The Treasury of Human Inheritance, a key publication in the history of medical genetics and eugenics and first published in England in 1912, recommended using the Mars symbol (♂), the archetypal manly God of War, to depict males and the Venus symbol (♀), the archetypal female Goddess of Love, to depict females. Francis Galton’s book Natural Inheritance, published in 1889, contains what he describes as a schedule for recording a family history in Appendix G. Not exactly a pedigree but same idea. In this schedule, “Father and his fraternity” are on the left and “Mother and her fraternity” are on the right. Galton, by the way, believed that males were inherently smarter than females.
Now we take a larger leap backwards in time to the 16th century and the establishment of the College of Arms, which is still active today and is the “official heraldic authority for England, Wales, Northern Ireland and much of the Commonwealth including Australia and New Zealand.” Essentially the College of Arms assigns a coat of arms to a family based primarily on family history. This institution has been collecting pedigrees for about 5 centuries, typically with the format of paternal lineage on the left/maternal lineage on the right.
Even in modern days, with a few exceptions, women are expected to display the coat of arms of either their husband or their father. If she chooses to display both, the husband’s coat of arms is displayed to the left or above the wife’s family’s coat of arms.
Another method of displaying a family history is the ahnentafel (usually translated from German as “ancestor table”). An ahnentafel lists a family history horizontally from left to right. Individuals on an ahnentafel are assigned specific numbers that cleverly allow you to determine the relationship to the proband without scanning through the entire table. The first ahnentafel was published in 1590 by the Austrian nobleman Michaël Eytzinger and it depicted the ancestry of Henry III of France. Note that the father’s lineage is above the mother’s lineage.
Medieval pedigrees, of course, were critical to establishing the right to rule. Whether or not you were going to be declared a Royal, or if you were Gene Chandler trying to become the Duke of Earl, all depended on your relationship to the current king or prince or count or whatever title you were aspiring to. Entitlement to the throne or castle depended on who your male ancestors were, so medieval pedigrees often omitted women other than to list them as spouses. Unless, of course, it was convenient in staking your claim to the throne, in which case a woman’s lineage was included in the pedigree to legitimize the claim, as in the case of a Carolingian pedigree drawn at the end of the 12th century.
It may come as a surprise to some that the Roman Catholic Church, an institution steeped in patriarchy, had a hand in emphasizing the importance of pedigrees and in shaping their format. The Catholic Church was the dominant authority in medieval Europe and played a role in regulating nearly every aspect of the lives of nobles and peasants alike. Going back to at least the 7th century, the Catholic Church had strong prohibitions against consanguineous unions, what they classified as “an impediment to marriage.” The bans extended well beyond first cousins. To guide prospective mates, the Church produced an arbor consanguinitatis, a generic diagram indicating how close various relations were to a given individual, often drawn with, you guessed it, the paternal lineage on the left and maternal lineage on the right. Of course, for the right price and for the right person, the Church was willing to permit such unions, and also to annul the same marriage on the grounds of consanguinity when that became convenient. As they did for Eleanor of Aquitane’s 12th century marriage and subsequent annulment to her relative King Edward VII of France, and then overlooked it again in her subsequent marriage to very-soon-to-be King Henry II of England, another of her relatives.
The Catholic Church also employed pedigrees to illustrate the genealogy of Christ, the so-called Tree of Jesse (Jesse was the father of Goliath-slaying David and a direct ancestor of Christ). This was especially useful for instructing those who could not read the Bible, which was practically everybody who was not a priest or a noble. The earliest known Tree of Jesse dates to 1086, though the tradition of graphically depicting biblical ancestry goes back at least to The Great Stemma, which is thought to date to the 5th century (The Great Stemma, like modern pedigrees, also has a left-to-right reading frame, starting with Adam). Jesse Trees typically depicted only the male ancestors of Christ, along with various other Biblical personages on the sidelines, cheering on the progression of the generations. These trees typically omitted Mary’s lineage (though often included an image of her) but did include the ancestors of Joseph, who technically is Christ’s stepfather and not his biological parent. Many include an actual tree emerging from Jesse’s groin, an image sometimes referred to as, ahem, “the rod of Jesse” (males and their delusional obsession with their penises, thinking they give rise to great trees!). It was not uncommon for kings to insert themselves into a version of a Tree of Jesse, likely in an attempt to show divine approval of their kingship, such as the elaborate family tree of England’s King Edward IV produced in 1461. The trees took on many forms over the years and can be found as illustrations in manuscripts, carvings, and on stained glass windows churches even to the modern day.
Another way that the Catholic Church may have influenced the appearance of a pedigree – and here I am speculating – is that it’s traditions may have been the source of placing the paternal lineage on the left and the maternal lineage on the right. A Catholic altar is often divided up into three parts – center, right, and left. The center is devoted to God. The right side – from the perspective of a priest looking out at the church – is devoted to Mary, the female. The left side is often devoted to Joseph, the male. Thus, think of looking at a pedigree as a priest looking out on a Church – paternal lineage to your left, maternal lineage to your right. Furthermore, in Catholic iconography, Mary is typically depicted as the right hand of Christ in Heaven. So it would be natural to follow that tradition when drawing a pedigree.
The story of the pedigree is more detailed and complex than I describe here, and probably goes even further back to the Roman Empire. What the story reveals is that even though a pedigree is an apparently objective and straight-forward graphical depiction of ancestry, it is suffused with the values of the people who construct them. The male bias in pedigrees was so embedded in Western European culture that it naturally spilled over into the architecture, appearance, and content of pedigrees. Sometimes those values are consciously articulated, as with the Task Force’s decision to recommend a gender-focused pedigree. More often, though, those values and biases are so engrained that we can’t see or perceive them, unless we march into the future with our eyes fixed on the past.
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- – The views expressed here are entirely my own and not necessarily those of other Pedigree Task Force Members or the NSGC.
I have resisted using family history questionnaires because for most patients those questionnaires probably just feel like homework assignments. Besides, I am not convinced that questionnaires really save much clinic time. More critically, the process of constructing a pedigree provides great insight into a patient’s understanding of genetics, disease, and family dynamics. And, truth be told, a questionnaire lacks a pedigree’s minimalist elegance and concise pictorial encapsulation of complex information. 
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