Mammals only have 2 genders. Sex is gender, gender is sex.
Occasionaly, there are freak accidents like XXY or hermaphrodites, but that's incredibly rare. That does not mean that gender is a "spectrum."
Gender aka sex is a biological fact. Gender, aka XX or XY chromosomes is a biological fact.
John Money coined the term "gender role" in 1955. Much of feminism is a rejection of traditional gender roles. But for some strange reason, people started confusing "gender role" with "gender" itself and started nonsensically claiming that gender IS a role, that gender is a performance, that gender is behavior. Meaning if someone changed their behavior they could change their gender, which is bullshit.
Aided and abetted by postmodernist philosophy and concepts like social constructionism, people in academia have had their head up their own ass for decades, and since "gender studies" isn't a real science, there have been a lack of real scientists calling them out on their complete and utter horse shit.
Gender roles are real, they are social roles based on gender (aka sex aka XX or XY chromosomes).
You could argue that masculinity and feministy are a "spectrum", but neither are gender.
Gender is not a social construct, but the concept of "gender identity" is (and arguably all "identity" is a social construct).
SJWs tell trannies "it's their body, their choice", but tell anorexics they need help.
SJWs tell trannies "it's their body, their choice", but tell suicidal faggots they can't do what they want with their body (destroy it).
SJWs say trannies don't have a mental disorder if it doesn't cause them any distress, but say pedophiles do have a mental disorder even if it doesn't cause they any distress.
SJWs accept such bullshit as someone claiming to have a different "gender identity" that differs from their sex, but would call anyone who claimed to have a "racial identtiy" different from their race, crazy.