My mum was, in many ways, a pretty shite mother, she yelled a lot, she loved running me down (calling me stupid, lazy etc when I really wasn't), sarcastic, mean and neglectful (not washing my clothes when I had peed myself, withholding meals etc).
However, I will be forever grateful that she never ever told me I needed to be kind to other people. My mother loathes and detests everyone on this planet and had no qualms telling me that I should do the same. As a result, my first inclination is to be extremely wary of most people. As such, I have never thought twice about saying no to things I don't want to do, telling people when they are being dickheads, standing up to shitty boyfriends/friends, walking away from assholes or whacking creepy gropers in clubs in their stupid ugly faces. I had some problems standing up to authority figures (bosses, teachers) when I was younger, but out of fear, not kindness but not these days.
As an example, I remember some guys were talking to my friends in the pub one night. These guys seemed extremely boring and kind of creepy, but my friends seemed to be laughing and having a good time so I left them to it. After chatting to them for two or more hours, my friends came over to me and said 'omg those guys are awful, but we couldn't get away from them.' In those circumstances, I don't think twice about telling such guys to leave me alone, and if they won't, to get the bar staff to throw them out. But so often, my friends will just put up with it and even tell me off for being rude if I ask them to leave us alone. I don't get it. THEY'RE the ones being rude by not leaving me alone when I request it so I don't really get why my friends are so worried about appearing rude.
While out and out misanthropy is not great either and I've had to learn to not despise everyone I meet on sight, I am so glad I was never a kind/nice/lovely person who hurts herself to avoid hurting other people.
For my troubles, yes, I get called intimidating, a bitch, terrifying, full of myself, entitled, up myself, a snob and so on. At times, I kind of believed maybe I was those things and wondered if I should be nicer - social pressure is a very hard thing to avoid. But I was told by a therapist that I actually just have extremely healthy boundaries and self-respect. There is also the possibility I have autism (I was told by the same therapist that I should go for tests) so maybe that's part of it - I don't see why I should be kind or polite to people who are not kind or polite to me, and I don't see why I shouldn't just tell the truth (within limits, of course.)
I don't know how to teach other people to be like this, however. I think the main thing for me is just that I refuse to be polite to anyone who is not polite to me.