Homeschooling.
Was very poorly homeschooled all the way until my sophomore year of high school. I had no friends, was socially stunted, and could barely do basic arithmetic. I ended up having to teach myself how to write and spell when I was younger, and to this day I'm extremely self-conscious about my terrible handwriting.
I think I turned out okay, but I still find myself struggling with a lot of things as an adult that I feel like should be basic skills, like reading an analog clock or doing math in my head. I wasn't really allowed to participate in pop culture as a kid either, since the point of the homeschooling was to be counterculture, so I don't really feel like I had a childhood. I've just kind of always felt like an adult, albeit maybe one that makes better decisions now.
To make a long story short, homeschooling turned me into an adult with massive amounts of anxiety, who just constantly feels weird and out of place. I feel like the personification of when someone moves all your furniture three inches to the left just to fuck with you, or like I'm constantly wearing a sweater that's itchy to me but no one else.