I personally think it started when I was about 6, my family would make fun of me for being a bigger kid and being scared of everything (I think caused by my dad showing me horror and saying it's real at a young age) and school was worse, the students sucked and was overly crowded (one big hall for Pre-K to senior year)  it was also overly religious, with days skipping math and science for bible study, I switched schools Wich was when it got slightly better, even as a 6yr old I felt useless and unwanted even though my mom showed love and didn't make fun of me (she did take anger out on us on occasion though),but my sisters, dad and stepmom did, me going step-dad to step-dad didn't help,each one felt out to get me, now I'm 15, and most of my family besides 2 out of my 4 sisters are not cruel anymore and I'm in much better shape, I still feel like my friends and family (besides my oldest sister who has moved out) hate me. They suspect I have imposter syndrome because I believe my every accomplishment is by luck. It sucks having one of the people you feel truly care about you gone makes it hard to calm down during stressful situations