Fact Check: Trump Executive Order Didn't Say All Humans Are Female, But Its Sex Definitions Lack Clarity
Claim:
In a January 2025 executive order, U.S. President Donald Trump inadvertently defined all humans as female.
Rating:
Claims spread that definitions of "male" and "female" included in a January 2025 executive order that asserted sex is established at conception accidentally classified all Americans as women. The claims were based on the common belief that all human zygotes and embryos begin as female.
The current scientific understanding of sexual differentiation no longer holds that female is the "default" sex for embryos. Rather, as is the case for male embryos, evidence suggests the development of normal female sexual characteristics in mammals depends on certain conditions.
That said, because the executive order did not explain what was meant by "belonging" to a sex, it's possible to interpret its definitions of male and female as either excluding all humans from both sexes or, alternatively, including all humans in both sexes.
In January 2025, rumors spread online that President Donald Trump signed an executive order targeting transgender individuals that inadvertently defined all Americans as women.
Trump signed the order, titled, "Defending Women from Gender Ideology Extremism and Restoring Biological Truth to the Federal Government," on Jan. 20, 2025, the same day as his inauguration as the 47th president. In it, Trump asserted that it was U.S. policy to recognize only two sexes, male and female, and that those sexes "are not changeable and are grounded in fundamental and incontrovertible reality."
In posts on social media platforms including Reddit (archived), Tumblr (archived), and Facebook (archived), internet users claimed the order's definitions of the terms "female" and "male" logically implied all humans affected by the order were female because all human embryos are female for the first several weeks of gestation.
(Facebook user @lara.bee.sharp)
As we'll explain below, the common belief that all embryos begin as female is not backed by the current scientific understanding of embryonic sexual differentiation. As a result, claims that the executive order in question inadvertently defined all Americans as female were false.
However, the wording of the executive order's definitions of "male" and "female" did leave room for interpretations contrary to the spirit of the order — for example, that all humans are neither female nor male.
The relevant part of the "Defending Women" executive order was Section 2, which contained definitions of terms relevant to the policy.
According to the order's definitions, as can be seen in items (d) and (e) in the below screenshot, "'Female' means a person belonging, at conception, to the sex that produces the large reproductive cell," while "'Male' means a person belonging, at conception, to the sex that produces the small reproductive cell."
(The White House)
Some (archived) internet users (archived) pointed out (archived) that zygotes — the technical term for fertilized eggs — do not produce any reproductive cells at the point of conception, which is true. In humans, females begin the multistage process of producing large reproductive cells (that is, ova or eggs) during the first trimester of gestation, while males do not produce small reproductive cells (sperm) until puberty.
However, a close read of the definitions shows that the executive order did not make any direct claim about zygotes producing reproductive cells at conception. Instead, it asserted that, from conception, human zygotes belong to either the male or female sex, defining the female sex as the one that collectively produces eggs and the male sex as the one that collectively produces sperm.
That said, the executive order did still leave room for creative interpretation of the definitions because of its failure to define the criteria for belonging to a sex.
What Does it Mean to Belong to a Sex?
One possible definition would be a genetic one, with all humans possessing XX chromosomes defined as belonging to the female sex and all humans possessing XY chromosomes defined as belonging to the male sex.
That approach would have had its own issues. There are genetic conditions, albeit rare ones, that can result in a person having an XX chromosome but male sexual characteristics or vice versa. There are also conditions that can result in nonstandard sexual genotypes, such as XXY. That said, because the vast majority of zygotes have from conception either XX or XY chromosomes corresponding to the types of genitalia they'll eventually develop, using genetics as the foundation for the executive order's definition of belonging to a sex would have some grounding in science.
However, the Trump administration did not use this definition in the executive order, which contained no mention of the words "chromosome," "gene," or "genetic."
That left room for another interpretation — namely, that what determines someone belonging to the male or female sex is the presence of anatomical characteristics associated with that sex. In other words, according to an anatomical definition, possessing a pen*s would make someone male, while possessing a vagina would make someone female. This is how doctors assign sexes to newborns.
The problem with this definition, in the context of the executive order's wording, is that no zygote has any of these physical characteristics at conception, nor does any embryo (the term for the stage of development beginning roughly the second week after conception) begin to develop these characteristics until around six weeks after fertilization.
How Does Sexual Differentiation Work?
For roughly the first six weeks of gestation, embryos are what scientists call sexually undifferentiated, meaning they have the anatomical potential to develop into either males or females. During the sexually undifferentiated stage, all embryos — regardless of their sex chromosomes — develop both Müllerian ducts, which have the potential to develop into female reproductive tracts, and Wolffian ducts, which have the potential to develop into male reproductive tracts. These ducts both terminate in a tubelike structure called a cloaca, which later undergoes changes that result in the development of the anus, urethra, and — for embryos that develop as female — the vagina. Embryos in the sexually undifferentiated stage also develop what scientists call bipotential gonads, which later develop into either ovaries or testes.
The process of sex differentiation is a complicated, weeks-long process that begins around the sixth week of gestation. At that point, if XY chromosomes are present, embryos begin to express what's known as the SRY gene. The expression of that gene leads to the atrophying of the Müllerian ducts, allowing the Wolffian ducts to start to develop into parts of the male internal reproductive system. By contrast, if XX chromosomes are present, embryos typically absorb the Wolffian ducts and the Müllerian ducts begin to develop the female internal reproductive system.
Because embryos only develop into males if the SRY gene is expressed, it's sometimes claimed that female is the default sex for embryos, or that all embryos start as female.
However, recent science suggests that claim isn't right. Based on studies of sexual differentiation in mice, scientists now believe there's evidence that the development of normal female sex characteristics in mammals does not actually proceed by default, but instead requires the presence of a specific protein called COUP-TFII. When that protein was not present, the authors of one 2017 study found, mice with XX chromosomes did not develop normal female reproductive systems but instead "became intersex — possessing both female and male reproductive tracts."
In summary, the current science doesn't back the claim that Trump's executive order defined all humans as female. However, the absence of any mention of chromosomes or genetics from the order's definitions of male and female does leave room for other interpretations inconsistent with the spirit of the order. For example, it's possible to interpret the order's definitions as meaning that all humans are neither male nor female — or, due to the presence of both Müllerian ducts and Wolffian ducts in early embryos, that all humans are both sexes at once.
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