I would bet that about 2/3 of the people in the English speaking world have not gotten that memo yet, or have heard it, but refused to acknowledge it.
It's been pounded into our heads for years now that gender is different from sex, and that's the entire premise behind transgender people needing recognition and acceptance. Their gender is different from their sex, and it is paramount that it be recognized as a separate thing in order for the activist platform to make headway.
I find it very frustrating when it is transgender people and transgender allies who so frequently conflate the two now.
The other 2/3 of the people to whom you refer are the ones who rejected the initial TRA position, and have consistently stuck by the view of gender being a polite synonym for sex.
Personally, I'm of the opinion that
gender identity is a construct, based largely on gender stereotypes driven by the assumption that gender expression and gender roles are something voluntarily chosen rather than something enforced by social norms of behavior.
- Sex is what your body is.
- Gender is what other people assume your body is.
- Gender identity is what you want other people to assume your body is.
Gender is comprised of two elements: secondary sex characteristics driven by biological factors including hormones, and expression driven by social conformity.
Secondary sex characteristics include the elements of a sexually dimorphic phenotype, including externally visible reproductive organs, breasts, facial and body hair, pelvic bone shape, skull shape, musculature, bone density, size of hands and feet relative to leg and arm lengths, width of shoulders relative to hips, and the distribution of fat across the body, among other elements.
Expression includes clothing and shoe choices, makeup, hairstyles, jewelry and accessories. Expression is frequently a factor in sexual selection, serving to advertise a person's sex in order to attract a mate. Note that it is not always a freely adopted expression, but is very often a reflection of social convention based on culture.
Gender roles are social expectations of expression and behavior that are correlated with the assumed sex of the person in question. Although some elements of roles can confer privileges, they can also be very confining, and can present very real barriers to individual success depending on the degree of taboo enforcement inherent in that culture.
Making all of that even more difficult are the elements that are a mix of sex characteristics and expression. Some behaviors are at least partially sex-linked, including the tendency toward aggression caused by testosterone and the tendency toward emotiveness caused by estrogen. Additionally, beyond the vocal pitch range defined by anatomy, there's a socially-reinforced expectation of higher voices for females and lower voices for males, which frequently results in people speaking outside of the midpoint of their vocal range in many cases. It's also reflected in the applied level of projection of one's voice, with women tending to temper their projection to seem more soft-spoken, and men tending to enhance their projection to seem more confident.
Sex is fixed in the womb, during fetal development. Some sex characteristics are present from that differentiation in the fetal stage (internal organs, genitalia), but many of them develop during puberty, triggered largely by sex-differentiated hormones.
Gender expression is learned behavior. It is highly influenced by gender roles within a culture, and can vary in strength significantly from one culture to another.
