So as someone who was born a guy but identifies femme for more than half of my life, I've thought alot about this question.
What part of my personality is defined by a gender, how much of my identity is integrated with my natural biology and how much of the way I feel is determined by society and psychology?
Having been raised a guy and never having come out to my friends and family, guy mode is my default, i consider it comfortable because I don't have to worry about judgement or scrutiny. It's a simple as toning down my expression of gender towards a more neutral way of presenting myself, and my biological masculinity (which I hate) actually acts like a cloak I can hide under. My deep voice, stubble, and physique mean that I can even express my preferred gender a little bit and I can avoid being outed.
Now as for my identity. I explored two thought experiments to examine how I feel about gender identity. The first involves a hypothetical world where you could undergo a complete body transplant, swapping your brain into a body of your choice, what would I do? Absolutely I wouldn't hesitate. If I could delete all signs of physical masculinity I would. I feel the feminine form is aesthetically pleasing and would wish to embrace it. Everything about masc features seem coarse and unwelcoming, where as with fem, features are typically softer. (I try to look at it from an objective point of view to help break down how much of it is internal vs external)
Removing the physical side of things the second thought experiment is a hypothetical scenario where everyone was transferred into a neutral identical body. One where it was impossible to discern masculinity or femininity from looks alone, how would I express my identity? In terms of style and outward presentation I would probably begin by swinging to the extreme of femininity and tone it back until I found a comfortable place. I don't think at any point I would swing towards masculinity.
The question remaining relates to my behaviour. What aspects of my personality are inherently "feminine" and how much of these are determined by societal norms vs objectively female psychology? Well I think for the most part I would just continue to be me, I wouldn't try to adopt any behaviours that didn't feel natural, I wouldn't try to incorporate any perceived feminine traits. It is more important to be true to myself as a person in this regard, everything else would feel fake (unlike outward physical presentation). But looking at this from a neutral perspective I think there are some biological personality traits and behaviours that are determined by physiology that I think are inherent to biology and influenced less by the perception of society. Some of these I feel inherently female, some I feel inherently male.
So people might stereotype men as being more competitive, but it's a stereotype routed in biology, the male hormone testosterone has been shown to increase competitiveness. In this regard I feel inherently more feminine, I abhor competition, and feel more inclined to help people out in a communal way. Interpret that however you wish, I just think its one of the few traits that set me apart from the typical guys I know. Not all men are competitive, but those on the extremes of masculinity "alpha males" tend to be competitive. On its own it's not compelling, but its one of the many things that make me feel femme
Similar to this, aggression is a testosterone dependent, and definitely something I do not relate to in any way shape or form. I get angry sure but I always try to avoid conflict as a personality trait and I don't remember any time I have ever gotten aggressive with someone. Women can get aggressive too I'm not saying it's inherently a masculine trait but it is linked to a male hormone.
A third thing that is related to testosterone is libido. Repeated trials show a correlation, and it is used to treat loss of libido in women post menopause, and in both men and women suffering loss of libido for specific causes. In this regard I am decidedly "masculine". I have and always have had a borderline insatiable sex drive.
Another well recognised effect of a sex hormone is emotional lability, as is experienced during pre-menstrual syndrome, and pregnancy, and is also a reported side-effect of the oral contraceptive pill. With myself I am 80% of the time in control of my emotions but I often have days/weeks with unexplainable emotional swings where there is no external influence to explain it, no underlying depression, no tiredness, no stress, no emotional stress, I can be perfectly happy but I can swing to tearing up at virtually nothing, to irrational anger, to intense affection all within the space of a day and it can last for several days. My partner once joked that it was like I was on my period, not being in control of my emotions.
Other things that are biology-based gender leaning behaviours include a maternal instinct. My experience with this one is difficult to pinpoint on one gender, but there is one clear difference I'll get to below. Basically, I think recently I am developing a strong nesting instinct. I recently moved in with my partner, I'm taking steps to make ourselves financially secure, and all the time in the back of my mind is the idea of starting a family. That's totally normal for men and women, but I feel incredibly weird saying this but I dreamt one time that I was pregnant and I haven't been able to shake the thought since. I genuinely never considered the ideq before that dream but if it were possible for me to carry a baby I 100percent would. I would want that connection to our child. What's even weirder is I've never spoken with my partner about having kids, it's all on my end as far as know, but we will someday.
I know loads of the above could be explained as normal for either gender, but together they painted a picture for me, and whenever I questioned my identity, and wondered if it was just a phase, I used these to try find a physical connection to how I felt and to reassure myself that my dysphoria was not rooted in unrelated mental turmoil.
Now many of these are hormone dependent emotions, oestrogen, testosterone, oxytocin, prolactin, will probably all have an effect on how a person feels. I have had a hormone screen for unrelated reasons (family risk factors for prolactinoma) and everything came back normal. I haver never had hormone replacement therapy. So I don't think its hormone balance affecting me, I think it's how my brain is wired to respond to hormones.
Well that's my experience of how I tried to deconstruct gender identity. I am open to all discussion on the above.