What isn't scientific (as is, no longer valid in scientific consensus[0]) is the premise that gender and biological sex are synonymous, and that, as your comment implies, transgender or nonbinary identity is a denial of science.
Just in case you're going to jump on to the title of the third article i posted below, note that it says gender is not just a social construct, rather than that it isn't such at all. I'll quote an excerpt from that article:
Evidence that gender has some basis in biology, though, in no way implies a strict gender binary, nor negates the existence of transgender and non-binary identities. Many biology-based gender differences originate from the hormonal environment within the womb, which is very different on average for boys compared to girls. But there’s a huge variation in these environments, says Alice Eagly, psychology professor at Northwestern University. “Within boys there will be a range and within girls there will be a range. To say it’s biological doesn’t mean it’s perfectly binary,” she says.
[1]https://medicine.yale.edu/news-article/what-do-we-mean-by-se...
[2]https://qz.com/1190996/scientific-research-shows-gender-is-n...
> In the 15th century gender expanded from its use as a term for a grammatical subclass to join sex in referring to either of the two primary biological forms of a species, a meaning sex has had since the 14th century
The point is, only one of the two sides in this debate are denying current (not 14th century) science, and it isn't the side you or yucky seem to believe.
Note that this link presents incomplete information as it seems to imply there is only one axis to the gender spectrum.