A couple years ago, I took a upper division biology class as part of my gender studies degree. The class focused on the biology of women (and, by extension, biology of human sexual difference in general), and I chose to look at the biology of transphobia for my final project. It was wild: so much bad understanding cloaked in language that looks like it’s plausible to someone ignorant of any biology concepts introduced after middle school–but absolutely weird if you’ve studied almost any college-level biology of sexual difference.
(Because everyone knows biology has color if we’re going to show pictures of it, right?)
While I am not a biologist (ask me about computer networks, not how bees reproduce!), I did learn enough in this to question the credentials of transphobia’s experts. If an undergrad in gender studies can do this, I can only imagine how an actual biologist trained in human sex differentiation would respond!
There are two threads of transphobic science: religious and secular. While both exist, I’m looking here at the religious thread, particularly that put out by the Institute of Creation Research (ICR), which, as you probably guessed, primarily promotes creationism (in contrast to evolution). But more widely, they promote quasi-scientific beliefs that support conservative Christian belief systems. One of these is, unsurprisingly, the belief in complementarity. That is that men and women compliment each other, but are uniquely different and have unique roles in society that spring, in part, from their biological differences. I.E. men are strong leaders and should engage with the public sphere of society, while women are great nurturers whose strengths are better suited for the private sphere. Trans people of course challenge this–if trans people exist, and we’re the gender we say we are, then gender roles (like male leadership) might not be as biologically fundamental.
To prop up this idea of complementarity, Dr. Jerry Bergman wrote an article the ICR promotes. This is typical of some of the more scientific-sounding arguments against transgender people, in that most people aren’t equipped to analyze it (most people have not taken biology classes on sex differences!), and instead relies on heuristics: that is, it sounds right, he’s giving citations, he’s a Ph.D., and, importantly, this supports a view that fits a worldview (either someone is uncertain what to believe about sex differences or someone already believes that biology is destiny). Importantly, it relies on an unwillingness to fact-check.
But before we start looking at the article, let’s ask, “Who is this Jerry Bergman?”
Who is Jerry Bergman, Ph.D.?
The byline on the ICR website for Bergman is, “Jerry Bergman, Ph.D.” So, what is his background? On creation.com, his bio indicates he has nine degrees! As for doctoral level degrees, he has two:
- Ph.D. in measurement & evaluation, minor in psychology, Wayne State University (1976)
- Ph.D. in human biology, Columbia Pacific University (1992)
The first one doesn’t make someone an expert on biology, and seems to be social-science oriented. That’s not a bad thing, and Wayne State University is a public university in Michigan that continues to be accredited. This is a respectable degree.
His Ph.D. in human biology, however, may be a bit less respectable. Columbia Pacific University was a distance education school (while not unheard of, it is highly unusual for Ph.D. study, particularly in subjects like biology which often require lab work). Worse, though, it was accused of being a diploma mill by California authorities and shut down for that reason. Quack Watch notes the high number of graduates that dabble in quackery. Even the US Government Account Office notes that the university was a problem, expressing concern about people with degrees from the unaccredited school working in federal government.
For someone who highlights his academic experience, this is a strange degree to include in the list. Most likely, he sought it and mentioned it to establish credibility as an expert on biology. While this doesn’t mean what he says is bullshit, it is a warning that we should approach his work with caution, perhaps verifying it when possible.
He currently works with the Institute for Creation Research (ICR) which is a well-funded (to the tune of $10,000,000 in annual donations). The focus of the institute is, obviously, creationism.
So that brings us to the article I wanted to talk about.
The Article and How Pseudoscience is Passed off as Science
The article, “Male-Female Differences Supported by Scripture and Science,” makes two sets of claims. First, it claims that there are differences supported by scripture, in particular the complementarity concept. I’ll leave analyzing the theology here to someone more equipped to respond to that. But certainly not all Christian theologians agree with Bergman’s views! (the competing view to complementarity is egalitarianism.
So, moving to the science…what can university science courses teach us, and does Dr. Bergman’s beliefs match up with science? Or is it just hogwash that sometimes passes a heuristic of “sounds like an expert?”
All Our Cells are Either Male or Female (XX or XY)?
Bergman states: “Genetically, except for enucleated (cells without a nucleus) blood cells, every human body cell is either male (XY chromosomes) or female (XX chromosomes).”
First, sperm and egg cells do have nuclei, but usually contain only an X chromosome (egg cells and roughly half of sperm cells) or only a Y chromosome (the other roughly half of sperm cells). Maybe Bergman doesn’t consider them part of the body? But even giving him this benefit of the doubt, no, not every cell with a nucleus contains XX or XY chromosomes.
First, chromosomal intersex conditions exist. Most people are aware of this these days, I hope, but for those who aren’t, people may have cells with chromosome combinations such as XXY. You can check out InterACT’s intersex definitions page to learn about the variety of intersex conditions, many of which involve different gene combinations than XX and XY.
But beyond that, did you know many cis, non-intersex women have Y chromosomes in some of their cells? Or that plenty of men don’t have a Y chromosome in many of their cells?
Many AMAB people have “mosaic loss of the Y chromosome.” Essentially, AMAB people, over their lifetime, lose the Y chromosome in some of their cells. That’s because cells don’t need a Y chromosome to survive–there is nothing on the human Y chromosome that is essential to life. Over time, these losses add up (since cells formed from the division of these cells also won’t have Y chromosomes). Thus older AMAB people in particular may be missing the Y chromosome. This may be a factor in some health conditions AMAB (assigned male at birth) people face. According to the mosaic loss paper linked here, it has been associated with infertility, cancer, and even early death. If you’re AMAB, you are pretty much certain to have some cells (from relatively few as a young person to a significant amount as an older person) that have no Y chromosome.
If an AFAB (assigned female at birth) person is pregnant with a male fetus, some genetic material from the fetus can cross into the mother, and thus some of this person’s cells may be XXY. Essentially, this person will have some cells with Y chromosomes! This can even happen when the person is unaware of a pregnancy that is spontaneously aborted (miscarriage) early in pregnancy.
So, ya, real life is much more interesting than Dr. Bergman would have us believe. If I was a theologian, I’d probably say that God is really creative and seems to love to throw wrenches into simplistic theories about biology (I mean just think of the platypus!).
Genetic Implantation as Sex Differentiation
Here we see Dr. Bergman’s understanding of human biology has some gaps, despite his diploma mill Ph.D. in human biology. He states, “After a zygote (a fertilized egg) is formed, thousands of genetic differences are created due to an epigenetic process called imprinting. This system turns off a wide variety of genes in males and a wide variety of other genes in females depending on whether the gene came from the father or the mother. The result is that many genetic differences exist between the sexes well before birth.”
This quote references a footnote at the end (because he’s trying to convey it’s scientific!). The book is J. B. Stump’s What’s the difference? How do men and women compare, copyright 1985. Note this book just talks about difference between men and women, as kind of a pulp-fiction trivia book (with the goal, according to the introduction, of addressing the “great identity confusion” of the 1980s). It’s certainly not a scientific book, and it does enumerate some legitimate sex differences, to get a full flavor for this book, it also has gems like this: “Males spend an average of fifty-two minutes a day on coffee breaks…Females spend about thirty-five minutes a day on coffee breaks” (p. 39, citing Susan Fogg’s newspaper article in the Honolulu Star Bulletin in 1980). It does not talk about imprinting, or how imprinting causes any of the supposed sex differences. Why a scientist would be citing this 1985 book is an open question, as there are scientific publications that talk about actual biological differences between AMAB and AFAB people, after all. I also would have picked something newer than this, because we’ve learned a lot about sex differentiation since the 1980s.
But back to Bergman’s main text after this autistic-long-form diversion (a phrase I first encountered in Leah Lakshmi Piepzna-Samarasinha’s writing, although they refuse to claim to have been the first to use this term; I make no apology for my mind’s sight-seeing), what is Bergman saying? He’s saying:
- Imprinting creates sex differences
- These differences are created after fertilization
- Imprinting turns off some genes in males, other genes in females
Bergman would have failed the undergrad course I mentioned I took.
Implantation is an epigenetic mechanism that turns off certain genes (I.E. it does not modify genetic code, but instead attaches a bit of material to the genes it wants to turn off). This is propagated through cell division, so any new cells will still have these genes turned off, with one exception. And the exception is important!
The exception is during the production of gamates–in gametogenesis. During this process, all these deactivations are essentially stripped from the DNA (so all genes would be “active”), and then some genes are deactivated in the produced gamates. Certain genes are always deactivated in sperm, a different set of genes is always deactivated in eggs. A likely reason for this is to ensure that DNA from a sperm cell and an egg cell is present, because the genes that are deactivated in sperm are active in the egg, and vise-versa. For example, some genes required for placenta development are deactivated in sperm. Different genes also required for placenta development are deactivated in eggs. Thus, the genes from just an egg or just a sperm cell, on their own, would have some essential genes deactivated and a placenta would not develop. But because we have two copies of most genes (one that comes from the egg, one that comes from the sperm), it’s okay if one is deactivated if the other copy of it is still active and can do it’s job, such as facilitating placenta development. Only some genes are deactivated — most genes are not imprinted in either egg or sperm — and thus you can have two active copies of most genes. But with the imprinted genes, you will have one that is active and one that is deactivated.
Importantly, this has nothing to do with sex differentiation. If a female is born, the selection of imprinted genes from the egg and from the sperm would be the same as if a male child is born. It’s all about ensuring that there are two sets of genes present, not about creating differences between males and females. Different processes do that!
Ambien Differences in Men and Women?
Bergman then goes on to talk about different reactions to drugs in men and women: “These [the imprinted differences?] genetic differences have profound ramifications in medicine. For years, only males were generally tested to determine proper drug dosages. Then it was discovered that the popular sleep drug Ambien is metabolized differently in females. Consequently, women initially obtained about twice the proper systemic dose, resulting in some female users being overmedicated, and this produced a rash of traffic accidents. One reason for drug dosage differences is due to major hormone variations between males and females.”
Before I write anything more, I’ll remind the reader that I’m not a doctor. Talk to your doctor about medical stuff, even if some random blogger on the internet says something that seems well supported!
But back to Bergman. In this, the claims:
- The differences from imprinting cause different reactions to drugs
- Only AMABs were included in many drug trials
- Ambien is metabolized differently in AFABs
- There was a significant increase in traffic accidents as a result of this
- Hormone differences cause different reactions to drugs
We already talked about imprinting, and how that is irrelevant to sex differences. But let’s look at differences between AMAB and AFAB people and drug reactions, particularly around Ambien.
While it is true some drugs are processed differently in cis men vs. cis women, we don’t usually know the cause of this. Is it hormones? Genetics? Something else? In the case of Ambien, it’s likely something else: weight.
It’s well known that smaller people often need less of a given drug than larger people. And it turns out that is likely the reason for the FDA choosing to limit the dosage of Ambian, as Helen Zhao, et al.’s, article discusses. In their article, they discuss how the FDA used a non-statistically-significance between men and women (when weight was controlled) in determining whether the drug would be adequately cleared from the body the next day (if it wasn’t, that would result in daytime sleepiness, which is obviously dangerous). Indeed, in one of several trials when weight was controlled, the data showed a non-statistically-significant showed that women cleared the drug quicker than men, the reverse of the trial the FDA used). Rather than conduct more trials to satisfy the FDA that the differences found between men in women in trials that didn’t control for body weight were due to the body weight, the drug company, to get the drug on the market quickly, simply reduced the dosage for women. The result? It’s likely that small cis men are receiving higher dosages than is safe! These men are likely just as “female” as the study assumes cis women are, at least when it comes to Ambien dosage.
There is no evidence that there was a “rash of traffic accidents.” There was a fear of a rash of traffic accidents if the drug were approved with the same dosage for men and women. Yet perhaps that fear was misguided, and the dosage likely should have been based strictly on body rate, without consideration of sex.
I can sort of forgive Bergman on this one. This belief, particularly at the time he wrote his article, was widely believed, even by doctors (and likely still is). But it shows how small legit sex differences become magnified, and the nuance behind those sex differences is wiped away by those trying to show major differences between men and women. Regardless, in this case, hormones don’t seem to be the cause of it. Indeed, hormones usually aren’t the cause, but because a lot people, including doctors, attribute almost magical qualities to sex hormones, the fear of sex hormones impacting drug metabolism was, for a long period of time, used to restrict women from participating in clinical trials. It was thought that AFAB monthly cycles would add noise to the data. Of course this also meant we didn’t actually learn if sex hormones had any impact on the drug, either. But as the Ambien example shows, just testing on women is not enough, without a nuanced view (such as controlling for weight differences when determining if a sex difference exists).
Women can’t Hold Their Alcohol?
Bergman writes, “Adult males and females also have different physiological reactions to alcohol due to variations in alcohol dehydrogenase—a detoxifying enzyme. Alcohol dehydrogenase breaks down ethanol, and as a result females exhibit higher alcohol metabolic rates than males. In other words, liquor tends to have a stronger effect on women.”
The reality is a bit more complex. The difference in alcohol dehydrogenase is in the stomach. A higher amount there is more likely to metabolize alcohol in the stomach (I.E. before it gets to the blood or brain). But what sex has more depends on age. Men get lower levels as they age, while women get higher levels as they age. Perhaps this is sex-hormone dependent, but it is certainly not a simple “men vs. women” difference, and the research is definitely not comprehensive. Other differences are based on muscle/fat distribution (which is, in part, dependent upon sex hormones) and blood volume (which is related to body size). Behavior also matters: people can build some tolerance to alcohol, so if one sex tends to drink more than another, it would be logical to assume that sex would have less effect from a given amount of alcohol. Regardless, specifying where this alcohol dehydrogenase is located is important — it’s not just found in the stomach!
But Bergman gets everything backwards here. Young cis men, for instance, have more alcohol dehydrogenase in their stomach than young women. That means they metabolize — or break down — alcohol faster. It’s not the cis women doing this, it’s the cis men! Higher metabolism of alcohol means less impact from the alcohol, which is the opposite of the claims by Bergman! This is a pretty basic mistake.
Regardless, this is an area of science that is still developing, and if I was trying to show major biological differences between AMAB and AFAB people, and there were tons of these, I’d pick one that is more supported by science.
Other Claims
Then we get into the reasons these claims are important to complimentarianists. We need to show why women should stay home and take care of the kids, while men should lead. Bergman does this by talking about how men and women respond differently on some psychological tests.
I’m not going to discuss this, because this doesn’t separate out the social and the biological in the claims (see Iris Marion Young’s excellent “Throwing like a Girl” article). Few claim there are differences between men and women in the world–the argument is whether these are biologically-inborn or are a result of the social context of our societies. If they are social context, then perhaps men could perform at the same level as women in the things men are generally bad at–and vise-versa.
For example, Bergman talks how women have more fine motor coordination and are better neurosurgeons and men have better gross motor skills and are thus better diesel mechanics.
But even the things where Bergman says women are better (neurosurgery, due to fine motor skills) are not supported by modern science. For instance, a recent study that did find some fine motor performance differences between men and women also noted that which sex did better varied based on age and test, with sometimes men doing better and sometimes women doing better based on task (axis across which movement occurred) and age. So are women better at fine motor skills? Or men? This study would seem to answer that it kind of seems random.
As for gross motor skills, Marion Young wrote about Throwing Like a Girl in 1980, talking about how social components impact gross motor skills, like throwing. But rather than relying on a 1980 paper (as sex differences are an area with evolving research, as I’ve pointed out when Bergman used old, often non-academic sources, as proof), let’s look at where Bergman’s claim comes from. In talking about differences in gross motor skills (and the connection to diesel mechanics), he cites a 1976 book (Lee and Stewart’s Sex Differences: Cultural and Developmental Dimensions). I suspect the world of female diesel mechanics was quite different in 1976 than today, even if today it remains a male-dominated profession. It is probably significantly easier to find well-qualified diesel mechanics in 2025 than in 1976! Despite the best efforts of people who believe in complementary, a lot has happened in 50 years. That said, among diesel mechanics, still only a single-digit percent are women.
Why is that? Gross motor skills, or something else?
Certainly any job working with heavy things is one that benefits from strength, and often men are stronger than women, but that isn’t a motor skill. It’s also one that changes with age, and, fortunately, there are alternatives where the relatively small strength differences come into play: there is plenty on a diesel truck that neither men or women can lift. The handful of things the average man can lift but the average woman can’t is likely pretty darn small!
I’ll also use my own experience here. I’m mildly competent as a garage mechanic. I find my difficulty is understanding how things work, not being able to manipulate a wrench. This is despite my extremely poor gross motor skills (tested as a child in the lowest 1% compared to my peers). If I can’t get the engine to idle smoothly, it’s not a motor skill issue. It’s a knowledge issue. That said, I trust my work with my life in some cases, whether it’s remounting and balancing a tire or rebuilding drum brakes. I’m not depending on my gross motor skills. I have tools to assist with that! I’m trusting on my knowledge, and my self-assessment of knowing what not to touch because of lack of knowledge and/or appropriate tools (no way am I going to work on a modern dual-clutch transmission!).
An alternative explanation to why women aren’t often diesel mechanics is that this isn’t seen as women’s work, in the same way child care isn’t seen as men’s work, and has nothing to do with strength, motor skills, or what size gametes someone produces. My best guesses as to why there are so few women in the field (as it seems nobody has this answer in research, at least that I can find, specific to diesel mechanics) is that it’s due to discrimination, gender roles we teach starting at a young age, and opportunities provided to children—I.E. who does Dad ask to “help” work on his 1965 Chevy, young Billy or young Sarah? The last explanation is one theory as to why so many computer programmers are male, after all, at a time when STEM participation by women is otherwise rising.
But There ARE Differences Between Males and Females
Yes, obviously.
But the point is that these differences tend to be exaggerated, universalized, and turned into reasons to justify mistreatment of women and others who don’t conform to patriarchal gender roles. We need good research into biology, and trans folks are part of that. We’re a key part of how we can detangle what is genetics, what is hormonal, and what is social. Sadly, as US politics have shown since Trump’s 2025 inauguration, in just the first week, the bro-culture has no desire to actually do this work (as I write this, government websites are removing information about previous requirements to test drugs on all sexes proportionally, encourage examination of issues relevant to women, and to look into socially-constructed differences between sexes—replaced by outright assumptions about the fragility of cis-women, the cited reason for an anti-trans executive order, which of course leads to women being even more excluded “for their own safety” down the road).
Gendered Thoughts 