On January 20, 2025, President Trump signed an executive order entitled “Defending women from gender ideology extremism and restoring biological truth to the federal government.” This executive order does anything but restore biological truth.
Let’s look at biological truth around sex determination.
Sex can be defined in many ways. (Sex and gender are different. Scientists understand sex as genetic, developmental, anatomical, and hormonal while gender is sociological and cultural.)
Chromosomal sex describes the sex chromosomes a person carries: most often, males carry X and Y chromosomes and females carry two X chromosomes.
Genetic sex refers to the genes that regulate the complicated process of determining the sex of an embryo. One of these genes, SRY, is located on the Y chromosome and is critical for sending an embryo along the path of male sex determination.
Gonadal sex refers to what gonads (sex cell producing organs) a person has. Most often males have testes and females have ovaries.
Genitalia can also be used to identify a person’s sex. For example, we think of a typical female as having a clitoris and vagina and we think of a typical male as having a penis.
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I alluded to the fact that sex determination is a complicated developmental process. Let me try to describe that process for non-scientists.
All embryos have the potential to develop into either males or females until around six weeks after fertilization. They are undifferentiated. We can know which chromosomes the embryo carries, and we could detect which genes the embryo carries but it is still uncertain if all the things we expect to happen at around six weeks will happen.
Typically, at six weeks, if an embryo carries a Y chromosome and the SRY gene on that chromosome is functional, the SRY gene turns on and the SRY protein is produced. The SRY protein controls the expression of many other genes (turns them on or off). When a functional SRY protein is made, it does just that—turns other genes on or off. Many of these other genes also encode proteins that regulate genes. Some of these genes lead the embryo down one developmental fork in the road: the undifferentiated gonads become testes. The testes then produce hormones that contribute to additional male-typical developmental events in the embryo. Thus, SRY begins a cascade of events such that many genes are turned on and the products of these genes trigger the events that lead to the formation of the kinds of tubes and ducts that will become male gonads, structures, and genitalia.
Conversely, different genes are turned on in embryos that do not carry an SRY gene, typically those without a Y chromosome, and those genes also trigger a cascade of developmental events. These events lead the undifferentiated gonads down a different fork in the road: development into ovaries. The ovaries produce hormones and altogether these events lead to the formation of female-typical tubes and structures like a uterus and Fallopian tubes.
The events leading to female sex determination were originally described as the default — what happens in the absence of SRY. While this is still close to what happens, the events that lead to female-typical sex determination are more complicated than a simple default developmental program. It is true that in the absence of properly functioning SRY and testosterone, female-typical genitalia develop. This idea of a default pathway has led some to suggest that the executive order defines all of us as female!
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Given how complicated these events are, it’s not surprising that there are situations in which things proceed in other ways. Let me give you a few examples. Sometimes, during sperm formation, the X and Y chromosomes swap a bit of their genetic information. This can result in the SRY gene moving to the X chromosome leaving the Y chromosome without an SRY gene. If these sperm are used in fertilization, the result is a person whose chromosomes are XY but they have ovaries and female-typical genitalia or a person whose chromosomes are XX but they have testes and a penis. In other words, chromosomally female/gonadally male and chromosomally male/gonadally female. Similarly, if the SRY gene is mutated such that its protein product fails to function, a person would be chromosomally male/gonadally female.
Some people carry mutations so that the receptor for testosterone is non-functional. In these cases, called androgen insensitivity syndrome, the SRY gene directs a developmental cascade that leads to testes formation, the testes produce androgens (male sex hormones, of which one is testosterone, but the rest of the cells of the embryo cannot “hear” androgens’ signals so the genitalia develop in a female-typical way. These individuals have undescended testes, a blind-ending vagina, and a clitoris. They are gonadally and chromosomally male but they have female-typical genitalia. There are even more unusual deviations in the typical developmental pathways that I wrote about in collaboration with two of my colleagues for the RJ previously. And, we haven’t even touched on brain sexualization, a process that is not yet well understood.
Biological truth is that sex determination is a complicated developmental process, controlled by many genes. It’s a process that usually proceeds in ways we expect but not always. It’s a process that doesn’t always land someone neatly into one of two distinct categories as the recent executive order suggests.
Considering this, I am distressed about my siblings in Christ who, for well-understood biological reasons don’t find a category into which they can fit. I’m worried about my kindred in Christ who don’t fit into the “neat” categories of this executive order for reasons we don’t yet fully understand. I imagine they, and the people who love them, are feeling frightened and uncertain. It’s a good time to remember that Jesus’ words in Matthew 25 apply to those who are left out of the categories this executive order defines when he said, “just as you did it to one of the least of these you did it to me.”
As a scientist, I’m distressed about the scientific ignorance this executive order reveals. As a Christian, I’m disappointed in my siblings in Christ who seem so eager to ignore biological truth and instead cling to a blatantly false belief of how the natural world works. I’m saddened that so many Christians actively refuse to see biology’s beautiful complexity and support a ham-handed political order as the way forward instead. We can do better. We must do better.
18 Responses
Sara, this is clarifying and helpful. Thank you so much.
Yes, clarifying and helpful. Science is an essential partner in a thorough theological analysis. No church’s HSR, or catechism for that matter, will ever be conclusive for all times.
Sara, Thank you for speaking as both a scientist and a person of faith. This is very helpful.
Thank you for educating us, Sara. I will have to read your essay several times to fully understand understand it—non-scientist that I am—but I will rely on your knowledge to help me have conversations with others about what is being done for political gain.
This is the piece I would have love to have referenced when, during listening sessions in our congregation about the CRC 2022 Synod decisions about human sexuality, I encouraged those in attendance learn more about the science of sexuality.
Thank you Sara for speaking out. You have given such a helpful explanation of what is known to be biological truth in this area. You have increased my wonder and amazement at the complex work of the Creator, which in turn leads me deeper into worship, and into loving all image-bearers of God.
A much needed perspective…thank you, Sara!
A bit technical, but the message is clear. Creation is black, white, and various shades of grey. And our call is to affirm and love it all. Thx for interjecting a bit of scientific truth into an era of governance that promises to ignore it. We’re in for a rough ride when it comes to science intruding into policy making.
Sara, thanks for this clear biological explication of the possible anomalies in human sexual development that can lead to different forms of intersex. These intersex forms are perhaps what Jesus referred to when he talked about “some who are eunuchs because they are born that way” in Mt. 19:12.
Thanks for this biological info. I do have one question: what kind of correlation is there between these biological “anomalies” and people experiencing gender dysphoria?
Thanks, Sara. I will be using this essay to help prepare my prenatal development presentation in developmental psychology.
This a very short video (and thus, also a bit simplistic) but it explains some of these ideas in a way that even my middle school science students can understand when I teach sex ed.
https://www.youtube.com/watch?v=z1Kdoja3hlk
God loves diversity, that is clear in the fact that there are over 300,000 different types of beetle…plus ecosystems, plant variety, and so many other homes for diversity on this planet! If God can get that geeked about beetle diversity, and we know that genetic mutations are the “happy accidents” that bring about that diversity, then it makes sense that we’ll have some interesting variety with sexual genetics as well.
Great question, David. The answer is sometimes. There are documented cases where a baby who is intersex at birth is assigned to one gender, raised as that gender, but decides, when they are old enough, that the assigned gender isn’t who they are. Most of the time, however, we don’t have a clear scientific (genetic/physiological/developmental) explanation for gender dysphoria. That doesn’t mean there isn’t one–just that we don’t understand the brain well enough yet.
Thank you for confusing our overly simplistic narratives. May you be heard in Washington, D.C.
Thank you. Thank you. Thank you. From those of us who are personally impacted by this hurtful rhetoric from the government (and the church), thank you. “By faith we understand that the universe was formed at God’s command.” Yet, “Who has known the mind of the Lord? Who has been his counselor? Who has ever given to God that God should repay him?” Living in the space of believing and not understanding should feel like home for believers. It is lonely. And it is holy.
Being the wife of a medical doctor for 54 years I know the proportion of the population with DSD (‘intersex’ condition) is 0.018%. Genesis 1:27 gives us God’s plan. “So God created man in his own image, in the image of God he created him; male and female he created them.” God’s word is the only Real Truth I consider discussing this topic. He created male and female in His distinct way to carry out His plan for all of life on this earth. That’s my only Truth! Sin produced flaws! God’s purposes are eternal. At birth with that 0.018% the doctor and the parents determine the sex/gender of that baby for life. That is love! All Glory for our male/female existence on His earth goes to our Creator God.
Thank you so much for your clear description of these kinds of biological complexities. As a high school Bible teacher who is no expert in biology, I’m very thankful for this. Whether it’s 1 out of 100 (or only 18 people out of 1000), it makes no difference to me. My calling as a Christ follower is to love my neighbor, no matter how marginalized in comparison to overall population.
Loving like Jesus begins with understanding – and understanding begets compassion. Thanks again for helping me understand this with more clarity.
It is tempting to view variations as deviations, and variants as deviants. Are persons with Downs Syndrome, Klinefelter’s syndrome, Turner’s syndrome, and other people with chromosomal variants also deviants? Are persons with ambiguous genitalia and intersex variations also deviants? Are those persons born with same sex attraction variants or deviants? Are these people to viewed as a consequence of the fall, or are they to be viewed as made in God’s image? Are we to view them a product or a fallen world or as children of God? Is there really a question of how Jesus would answer these questions?
Thank you for explaining the biology of how God’s creatures are fearfully and wonderfully made