Does this mean I look younger than my age?

*I'm one of the people with the weird ages, not 45+

So I'm 25 1/2 and always thought I looked my age, not younger. I was worried I could look older actually. But I did notice over the summer for some reason that people that I don't know thought I was younger. Some used informal language used for teenagers or very young adults (not in an English country, in language there's different respect/familiarity levels of speech) when talking to me, or asked if I was a student. I don't think I dress younger than my age but I don't know, maybe it's how I hold myself? don't know. But what really made me think about this and still weirds me out a month after is that I went with my dad to some government service, and to modify a file the lady asked me if I was a minor or an adult. Mentally I was like huhhh how? That took me aback and made me rethink how old I look.

I'm not short at all, I'm average weight, for reference. I don't see how I look like someone who could be in high school. But I don't know.

Do you think it sounds like it's probably my face mostly? Or other behaviors/clothes?

Does this mean I look younger than my age?
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