male blackface good god.

leaving that aside, your sibling might be trans, or they might not be. there's nothing here to suggest that they aren't.

if you poke through this sub, looking for the "Am I/Are they trans?" posts, or the "How did you know you were trans?" posts, or the "What is being trans like for you?"--I think you'll see that it works out in a variety of different ways for different people.

I think one common thread is that it's often a process. figuring out what you are, how to be what you are, and then how you are going to present what you in interaction with the world around you can be difficult in this context. there is not a lot of external support, or common cultural tropes to hang onto--and some very really dangers and negative pressures.

think of it as being gay in the 1970s, if that's helpful.

as for not seeming to conform with "male culture" (which I am going to assume is a mixture of socialization and cultural norms)--there are plenty of cis-men that don't. and more than that: being trans can mean that you don't necessarily get the full standard experience for your gender (to the extent that such a thing exists).

at the very least, this can mean that sometimes things that might be seen as automatic "tells" or standard behaviors for a given gender are not intuitive.

more than that, it can also mean that eventual presentation may be non-standard compared to the cultural norm for... kind of the same reason that someone looks at their own country differently after they've lived abroad.

so, there is some context.

as a side-note: it seems to me that you're trying to make a cultural appropriation argument here. is that hill really worth dying on, with regards to this?