Oh my goodness,
@SchrodingersMeerkat , what a thing for your mother to say to you

...I'm so sorry.
I certainly don't get the impression that you are "mean" at all.
...Anyway, I find "Autistics are mean" to be a gross generalization.....everyone is different (as has been previously mentioned), but I think a person being
inherently "mean" is very rare. I don't believe anyone is
born "mean." Maybe someone (hypothetically) could have had adverse life experiences that negatively impact the way they interact with others, but that doesn't make them "mean" - in fact, I think it means they're that much more in need of other peoples' support and unconditional love/acceptance....otherwise, how can they eventually feel safe enough to show the "nice-ness" that was always there?
(I really hope what I'm saying makes sense - I've been at work all day, used a lot of spoons and I'm pretty tired

)
...But anyway, to answer the original question, no, I do not think that being mean is just part of being autistic. In fact, lots of folks here, and other autistic people I know on other social media platforms, are some of the nicest people I know.....much nicer than a lot of NTs I've known, anyway.
