I daresay that the author is conflating terms a bit in the blog post, and there’s no question that s/he(?) is letting his/her interpretation of the evidence be heavily influenced by his/her worldview.
I think the author’s most legitimate point is that societies tend to develop rather narrow, stereotypical concepts about masculinity vs. femininity; this is something that I won’t dispute. From a purely functional, reproductive standpoint, however, there are only two sexes, male and female. As it turns out, though, the development process is an intricate, complicated dance that still isn’t fully understood, and any number of abnormal events can lead to abnormal results; the people whose biology is impacted by these abnormal results are collectively referred to as intersex. Individual intersex conditions are fairly rare, but if you put them all together, intersex people make up about 1-2% of the human population.
In the vast majority of cases, sex is determined by the SRY gene on the Y chromosome, which triggers the differentiation of the gonads into testes about 6-8 weeks into development; prior to this point, the gonads are undifferentiated, and without a functional SRY gene present, they will develop into ovaries. However, any number of abnormal events can affect the final outcome: the SRY gene may be damaged or lost in an XY zygote, preventing male development, or it may be be transferred from the Y chromosome to the X chromosome during meiosis, resulting in an XX male. Additionally, a person may have more or less sex chromosomes if meiotic division doesn’t split the father’s genetic material evenly between the gametes (ex. an X female or XXY male). Further abnormal situations can occur if certain developmental events (ex. the descent of the testes) fail to be properly executed. Depending on the exact situation, the final person may appear normal but suffer infertility, deal with mild to severe impairments, or (if the genetic/developmental abnormality is too extreme) be miscarried. Even when everything goes normally, however, and we end up with a fertile XY male or XX female, the interaction between genes (which are more akin to dials than on/off switches) and environment leads to a broad diversity of physical, mental, and psychological results.
Okay, all that aside (and it’s a majorly simplified explanation), we as Christians are left with the question of how to deal with the messiness that is biology. I don’t believe that the correct response is to take the exceptions as proof that the male/female model is wrong, nor do I think trying to force-fit people into a mold (which has tended to be the traditional approach) is the best idea. From my perspective, then, the best option is to treat the male/female dichotomy as basically correct while avoiding the temptation to say that men must be like this or women must act like that. At the same time, we must acknowledge that people who don’t fit the typical mold are just that… people… who are made in the image of God and deserve to be loved and valued as much as anyone else. And in the end, sex and sexuality is an earthly affair; at the Resurrection, there will be no marriage (Matthew 22:30) except that between Christ and His bride, the Church, and all the incongruities between body, mind, and spirit will be sorted out by the God who makes all things new.