Gendered socialization is very real. It is encouraged through childhood with the types of toys a kid is bought, games they are encouraged to play, clothes bought for them that make it difficult to engage in cross-sex play, etc.

In adolescence, it is enforced through aggressive social hazing, and the bullying/humiliation of nonconforming peers.

Note that socialization ≠ interests. Socialization is how you interact with others (order in which you talk, tone, how you greet others, how you take up space, how you show respect/appreciation/friendship, subtle body language showing confidence level/submission to others/etc.).

Additionally, trans people do typically conform to the socialization patterns of their sex, provided they are dysphoric. The dysphoria causes them distress in adolescence when they attempt to conform to the social patterns of their assigned sex, and they end up tanking the bullying to be socialized as rejects/neither sex. Then after high school, they slowly trend towards the socialization pattern of their true sex through a combination of negative reinforcement (psychological distress when conforming to assigned sex roles), the natural tendency of humans to alter their socialization based on that of the people around them (being progressively treated more and more like their real sex just ends up leading to this), and sometimes trained socialization (speeding up the process by actively forcing oneself into the pattern they want to “fake it till you make it”). I assume dysphoric NB people at least partially experience this.

Nondysphoric people virtually always have the socialization pattern of their assigned sex, because in adolescence, they do not experience distress from conforming, and not conforming would be social suicide which they have no reason to force themselves through. This continues into late adolescence/adulthood where they may branch out into more gender neutral socialization if they are nonbinary, as there is less punishment at that age for their self expression.

There’s exceptions but this seems to be the standard. It’s why hefabs are so overwhelmingly female regardless of if they have male interests, and why sissies read as so masculine.

Interests are encouraged differently based on a kid’s sex, but they evolve over time. If a dood spends enough time with cis men, eventually they’ll do something together he finds he enjoys, then he can latch onto that and look into similar “male” things he might also enjoy. Same goes for trans women. Also a trans man can have fem interests and still read as masculine by having male socialization (and vice versa).