Because you know that genders determined by XX chromosomes and XY chromosomes.
The relevant edge-cases actually suggest an elaboration on that, being that Men are defined by the effects of androgen hormones, which have the producing anatomy developed by the presence of the Y chromosome, and Women are defined by the properties of the human body
without androgens
alongside the effects of estrogen(s) that are produced by the anatomy that forms without the Y chromosome's prenatal influence.
Among those edge cases are androgen insensitivity conditions, which can generate a
fully functioning biological female (as in "only discovered to have the condition
after giving birth") with XY chromosomes who's only
initial aberration is lack of response to androgens as a genetic male zygote. If we knew how to manufacture functioning ovaries with such a condition, it'd be trivial from there to have transwomen be in a state directly akin to that post-operation to end up outright female.
Of course, this also means male/female is a bi
modal situation, with outliers that fall
between the two (and as such "non-binary" genders that lie outside are either postmodern bullshit or religious castes, which are just a different kind of ox feces), while genders are defined by the commonality of these extremes of sexual dimorphism, as societal properties are determined by the degree of plurality. But that takes a lot of nuance, and whenever people start trying to play politics using science, nuance is usually the first thing to die...
Again, going a bit further to build the definition instead of taking only "common knowledge" surface-level scientific data creates a definition that includes the edge-cases naturally, rather than being undermined and eventually disproven by them.
Okay. So at which point should you be able to kill the baby?
You were saying at 8 weeks, right?
He said 8 weeks was the stopping point, as that is when the neurology begins to exist. Before this point, the idea is that the genetically-distinct flesh is not a
person.
The purpose of the question you're repeatedly refusing to answer, that of the personhood of a headless body, is that the notion of personhood I understand Abhorsen to take is that life with personhood value is defined by the central nervous system. A nerveless fetus thus has personhood value
inapplicable, while grown non-human animals have the notion be something that applies, but with a lesser value that humans.
The underlying morality of it, to my understanding (please correct me if I'm wrong on your views,
@Abhorsen), is that it is only immoral to destroy an organism
in its own right (as in, not considering the secondary effects of the destruction, which is where the morality of destroying flora and microbes lies) if it has reached the point where one can ascribe notions of suffering to it. Organisms that lack any means of cognition and reaction do not reach the threshold of "life" as sufficient for moral weight.