The thing about the TERF concept of gender socialisation is
not only is it internally incoherent (in that it posits a very arbitrary stopping point after which I guess how you're socially received and responded ceases to matter at all?)
but also if we accept it as What That Term Means it makes any discussion of socialisation in any context kind of incoherent??
Socialisation is a process by which social structures are reproduced (a process, which is why 'socialisation' and 'social reproduction' aren't synonyms). It includes both the teaching and the learning of social roles, and it's about how we internalise behaviours and attitudes in response to what's socially incentivised, punished, or idealised.
It's got a lot of components, because it's Basically Everything About How You Move Through A Social World, but some important ones are:
The rules and ideas we're taught about what different sorts of people are
The self-image we build out of what people tell us about ourselves
The behaviours that are rewarded or punished
The things that are treated as normal, unusual, or taboo for us to explore
a) a nuanced sense of self which is in conversation with the social responses we get (doesn't necessarily align with, but is shaped by, how others view us)
b) a complex subconscious understanding of the social rules and behaviours we are expected to follow, which is significantly deeper and denser than what we could verbally explain
The TERF version of gendered socialisation is, effectively, focused on formative training. and that is part of what socialisation is but only a relatively small part. The TERF version is only concerned with external incentives, and it operates from the assumption that you get socialized once, in an extremely consistent way, and it is both time-limited and irreversible.
One way in which this is incoherent is that gendered socialisation isn't a one-and-done.
Cis people, as well as trans people, are resocialised at multiple points in their lives. For example, a lot of the struggle of adolescence is that the gendered behaviours of a child are not acceptable in the gender behaviour of an adult. Similarly, a lot of women at menopause find that behaviours which have previously been rewarded become unacceptable and vice versa, and that the modes of interaction with younger women, peers, young men and men their age have shifted substantially. What it means to be gender-conforming changes over your life (an example might be how hyper-femininity in a little-girl mode can become a nonconformist gender expression in adult women, or how grannies are granted social permission to be much more pragmatic and hands-on without undercutting their womanhood).
Socialisation is a constant process, and as your positionality changes, so does your social experience. A 13 year old girl may know all the spoken social etiquette of being an adult woman; it still takes years of being received and responded to and thinking of herself as a subject of womanhood to start to get a handle on the nuance of navigating the social landscape of womanhood. During that time she will be clumsy, she will over- or under-perform signifiers of womanhood, she will struggle to locate herself within the idea of A Woman, and as a result she'll often be considered awkward or annoying or incomprehensible.
Generally, the teenage girl gets an amount of grace for the fact that this is a socially accepted learning stage. But that doesn't stop her or her peers being neurotically aware of where she's not measuring up, where she's misjudging social cues, and so on.
The teenage girl is being socialised as a woman. It's a new learning process. But that doesn't mean she wasn't subject to gendered socialisation before that! Before she was expected to resocialise as a woman, she was already almost always socialised as a girl child. Even if he parents tried to protect her from it, gender is embedded in the social language of almost every culture, and so her behaviour, her approaches and her sense of self have been shaped by being raised as a Girl Child.
But she's not a Girl Child when she's 25 - she's a young woman, and the behaviour and affect and presentation which was ideal in a girl child is received as inappropriate and aberrant as an adult. Obviously she remembers being socially a Girl Child. She may remember the rules of being a Girl Child - more likely a lot of them have been overwritten by the process of learning how to meet the social role of an adult woman.
(The same is extremely true of boys as well, btw. I focus on feminine socialisation because it's what I have most experience with but boys and men resocialise at several life stages. These cisgender transitions are more obviously marked in cultures with coming-of-age ceremonies, like a naming ceremony or a coming out, but even then I think they tend to largely focus on the earlier transitions and not so much the gender transitions in adulthood, of which there are several)
For the record, this isn't new and it's not originating from transfeminist thinkers. This is what de Beauvoir means when she says "one is not born, but rather becomes, woman"
(de Beauvoir is also not a pure advocate of social construction of gender, she has a lot of evopsych and biological fatalism mixed in there. but the second half of The Second Sex is largely concerned with the socially enforced Ages of Woman - how women are socialised into distinct gender roles dependant on age and stage, and how social behaviour and self-image are reinforced through socialisation)
So like, inevitably the question has to be: we can see that in cisgender people, socialisation is dynamic. We can see that one moves from one gendered social role to another. Why and how would the clock suddenly stop for a Boy Child transitioning into a Young Woman, or for a Middle-Aged Woman transitioning into an Elder Man? By what mechanism could cis people be resocialised frequently throughout their lives based on how they're socially received and how they understand themselves in relation to social mores, where a trans person who both understands themselves and is met as their transitioned gender is fully excluded from that?
It's incoherent. Like it is literally incoherent. This extremely flat and static idea of gendered socialisation is often held up as evidence of why even a cis-passing trans person is existentially Not Their Gender - but that doesn't make sense with how socialisation observably works.
What causes me to be socialised as a woman is
a) that I am received as a woman, and subject to the incentives and disincentives of social behaviour for women
b) that I understand myself as a woman, and reflect and internalise my sense of self through the lens of how women are socially expected to behave
But like. There is no tangible difference between my positionality there and the position of a trans woman. She has past experience of not being socialised as a woman - but so do I.
When I was 10 I was not a woman. I looked at women and tried to learn from outside what a woman is and does, because I had understood myself as a girl who would at some point expect to be a woman, but I wasn't socialised as a woman. I was socialised as a girl. If I behaved and presented as a woman that would have been received as inappropriate, or humorous, or odd, or unacceptable. As a cisgender girl child, womanhood was something I viewed and learnt about from outside, with the potential of moving into it later.
What about being partially or fully socialised as a boy-child or as a man precludes having the same experience? You can learn about it from outside and later resocialise from inside.
One thing I find super objectionable about the acceptance of the TERF definition of gendered socialisation is that I think it makes it way harder to acknowledge the common realities of gender transition.
Which is to say, at risk of starting shit: I think that when they socially transition, trans women are coming from being socialised as male and trans men are coming from being socialised as female. And social transition is very much the same process of gendered resocialisation as most cis people experience in adolescence (and middle age, and old age), which is to say that it's a steep learning curve as you move from watching from outside to trying to navigate a lot of complex unspoken rules.
People undergoing social transitioning - whether from opposite gender socialisation or from child socialisation - often start out struggling with the nuance of when physical or emotional intimacy is and isn't appropriate; of the social behaviours that are suitable for spheres they were previously excluded from; of the very fine detail of social mores and expectations that go unspoken and look effortless from outside. We carry in the rules we've previously learnt were correct, cause we have to behave in some way, and there's a years-long process of learning where they still apply and where they've changed with our positionality. It does take a long time, and the process of trying to realign how you move through the world is frequently hurtful, embarrassing, awkward, neurotic, and super super super exhausting and frustrating. You know that you already are the thing you're striving to become but you still seem to be doing it wrong. And it often feels like that for years. I mean socialisation is a constant process but over time you settle yourself into it - you largely learn your end and get on an even footing with your peers, and if the rules or your positionality changes you have a bit more solid footing to adjust to it.
But I really don't know what you'd call the process by which this social transition happens if not gendered socialisation. It's the combination of how you're socially recieved and how your sense of self is filtered through the lens of social experience.
A common response to the TERF version of gendered socialisation is that you're not socialised as male if you understand yourself to be female, and vice versa. To a degree that's true, but socialisation isn't a binary state.
Simplifying - socialisation consists of both a) how others see you and b) how you reflect your social surroundings in how you see yourself.
If you understand yourself as a girl, but you are understood and treated as a boy, that does impact your social experience. You are punished for expressing feminine behaviour as a boy, and behaviours and affects which would be encouraged in children seen as girls are punished in children seen as boys (and vice versa). That does affect your sense of self - not necessarily in that you accept that you're a boy, but that you accept that you're a girl who's treated as a boy and will be punished and rewarded in line with how boys are meant to socially move through the world.
The thing is that doesn't say anything about your innate reality. It says something about social survivability. Socialisation is how we learn to navigate and survive a social world. It teaches you what parts of yourself will be accepted and what has to be managed or suppressed in order to maintain social safety and support.
The worst thing about the TERF conception of socialisation is that it's flattened down to an innate trait about you. A True And Unchangeable Fact. In this conceptualisation, saying 'you have male socialisation' and saying 'you are innately male and always have been' are the same sentence. But this is so fundamentally at odds with what socialisation actually is that it makes me see stars.
Socialisation isn't about a static fundamental self, it's the method by which we learn what will be welcomed and what will put us in social danger. The lens we view ourselves through is also shaped by that - if I act in a way that is socially unacceptable for a woman, not only am I in danger but it's something Wrong About Me. If I'm trying to understand who I am and who I should be, I necessarily reference my social experience and conditioning - but socialisation is the lens, not the object.
I filter my view of myself through someone who both is a woman and moves through the world as a woman - I reference myself against it. Sometimes I say 'this thing about me is wrong, it doesn't fit the social schema of womanhood' and sometimes I say 'I'm like this and it's not in the social script for a woman but I am a woman so it's a thing women can be.'
that's more complicated obviously if you both know you're a woman and know you're being recieved as a man. But this is also where we need to acknowledge that socialisation is complicated and intersectional, and that agreeing with how you're seen isn't a necessary component of socialisation.
Especially when it comes to socialisation as a member of an underclass - socialisation as female, as gay, as Black or racialised, as working class, etc, how socialisation shapes our internal sense of self is often through direct conflict.
In Black Skin, White Masks, Fanon talks at length about this process - about how he as a Black child was socialised to understand Black and Creole people as inhuman and threatening and White French people as human and innocent, and the ways that being socialised to behave as if these things are true creates enormous internal conflict and a fractured sense of self against a lives experience of being a human and vulnerable and intellectually complete person who is under regular threat from white people.
de Beauvoir pulls out something similar about womanhood - a woman is socialised to perform and understand herself in reference to the idea that women are unpeople, incapable of independent thought and human feeling. But a woman also necessarily understands herself as a person with thoughts and feelings. Her internal sense of self is therefore structured around the impossibility of being what she's socialised to be. As with Fanon, there's a fracturing sense of self, which she can respond to by pushing herself to achieve womanhood, by understanding herself as a failure, or by cognitive dissonance.
What I'm saying is that being Socialised As is not the same thing as internally Experiencing Yourself As. Socialisation is necessarily reactive and mutable and it doesn't necessarily at any point align with your fundamental self.
You can move through the world as Thing A your whole life, and it will shape you and traumatised you but it will not fundamentally stop you being Thing B. But also the fact that you are Thing B will shape your experience of socialising as Thing A.
'but if I know internally that I'm a man then I'm not being socialised as a woman' is a reasonable outlook, but socialisation is an interactive process. How people see you will shape how you see yourself; how you see yourself will shape how people see you.