I hope you're not confused about sex and gender being different things.
But assuming you are asking for the scientific basis of sex (I'm sure you will actually read them
)
Brain Sex in Transgender Women Is Shifted towards Gender Identity
Transgender people report discomfort with their birth sex and a strong identification with the opposite sex. The current study was designed to shed further light on the question of whether the brains of transgender people resemble their birth sex or their ...
www.ncbi.nlm.nih.gov
The impact of sex on gene expression across human tissues (note, they mention 13,294 genes connected to sex)
Many complex human phenotypes exhibit sex-differentiated characteristics. However, the molecular mechanisms underlying these differences remain largely unknown. We generated a catalog of sex differences in gene expression and in the genetic regulation ...
www.ncbi.nlm.nih.gov
.
Sexual Differentiation (refers to the many stages of sexual development where differences can arrise)
The landscape of sex-differential transcriptome and its consequent selection in human adults
Background The prevalence of several human morbid phenotypes is sometimes much higher than intuitively expected. This can directly arise from the presence of two sexes, male and female, in one species. Men and women have almost identical genomes but are distinctly dimorphic, with dissimilar...
bmcbiol.biomedcentral.com
Genetic Architecture of Sexual Dimorphism in Humans
Males and females differ across a broad spectrum of morphological, physiological, and behavioral characters. In fact, sexually dimorphic traits typically contribute the largest component of phenotypic variance in most taxa that use sex to reproduce. However, we know very little about the...
pubmed.ncbi.nlm.nih.gov
If that's too hard to read, this guy summarizes some of the ideas.
The video is way off What these do you say. The study is seem to indicate a strong Tennessee to generic determinism. That is a huge number of Organs react to other what is male or female. Sex has a far greater Biological order did we ever imagined
Many complex human phenotypes, such as anthropometric traits (e.g., waist-to-hip ratio), exhibit sex-differentiated distributions; disease features such as prevalence, progression, age of onset, and response to treatment often differ by sex (
1–
5). These sex differences have been variously attributed to hormones, sex chromosomes, genotype × sex effects, differences in behavior, and differences in environmental exposures (
6), but the mechanisms and underlying biology of the sex differences remain largely unknown. The Genotype-Tissue Expression (GTEx) project (
7) provides an opportunity to investigate the prevalence and genetic mechanisms of sex differences in transcriptomes and to identify how sex and genetics interact to influence complex traits and disease. The analyses presented here characterize sex differences in a relatively large population sample, including many tissues that generally lack characterization. Because the causative tissue is unknown for many diseases and disorders, analysis of this diverse tissue set can serve as a powerful resource for investigations into the basis of sex-differentiated phenotypes.
or In other words
Okay kiddo, so sometimes boys and girls can be different in the way their bodies look and work. For example, boys might be taller than girls, or girls might have wider hips than boys. Scientists want to understand why these differences happen, so they did a big study where they looked at how different parts of the body work in both boys and girls. They looked at things like how their muscles, bones, and organs work together. They did this in a lot of different people and in a lot of different parts of the body. This can help scientists understand why boys and girls are different, and maybe even help them make things better for people who are sick.
In the context of one study, "sex bias expression" refers to genes that are expressed (or activated) differently in males and females. The expression level of a gene can be measured by the amount of its corresponding RNA, which is a molecule that carries the genetic information from DNA to the place where proteins are made. If a gene is said to be "sex-biased," it means that its expression level is significantly different between males and females in a certain tissue or cell type. This sex bias can be either upregulation (more expression in one sex) or downregulation (less expression in one sex). The study found that 37% of all genes exhibit sex-biased expression in at least one tissue, which means that there are a lot of genes that are expressed differently between sexes.
This is not gender fluid. Points at least partly to the opposite.
ps
BMC biology a good journal it seems:
BMC Biology is a peer-reviewed scientific journal that covers research in all areas of biology. The journal is published by BioMed Central, which is a publisher of open access scientific journals. BMC Biology is considered to be a reputable journal in the field of biology, and its articles are generally considered to be of high quality. The journal has a good Impact Factor and is indexed in many major databases such as PubMed and JCR.
It is considered as a good journal for publishing research in the field of biology, and researchers can consider it as a good option for publishing their work. However, the journal's reputation and impact can vary depending on the specific field or subfield of biology. It is always recommended to check the journal's impact factor, acceptance rate and the quality of papers previously published in the journal, before submitting a paper.