I have 2 writing styles. If I take my time and really concentrate, it can be very nice. Birthday cards and letters to school are always neat. But, my natural handwriting is not good. I don't even think the letters form naturally at all and joined up writing is not easy for me. I often have to go over bits to complete letters that haven't been formed correctly, so that I can read it myself.
My husband, who is definitely BAP, but would not meet the criteria for AS, has terrible handwriting. It's really illegible and, if he writes a card, he usually makes a mistake and it looks awful. He's unable to make his look neat, whereas I can. I would say he has undiagnosed dysgraphia (as well as undiagnosed dyslexia). He holds a pen weirdly too, with his thumb and first 2 fingers like a pincer, not with the pen resting on his middle finger, the way most people do.
Our daughter has the best handwriting in her class and, of the 3 of us, she's the one with the most obvious ASD. Her teacher told me that her writing was so beautiful that it made her feel quite emotional. My Mum, who I suspect as being on the spectrum too, used to win school prizes for her handwriting (it's like calligraphy).
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"We act as though comfort and luxury were the chief requirements of life, when all we need to make us really happy is something to be enthusiatic about." Charles Kingsley