i guess it can be a country to country situation. i was a shy kid and i was left alone for the most part. the only people doing anything were the ones that knew i'm gay.
it's possible for a shy kid to be picked on by like a couple people that spot him and see him as an easy target. but for the whole school to bully them, that kid's gotta be bringing in some attention. standing out in a negative way will get people to make fun of you. and if your parent is a teacher, there's a likelihood that anyone that knows it will pick up on you for it. but unless you got a weird relationship with them at school, it'll be pretty harmless stuff. might get a few weird looks calling a teacher dad, from kids that didn't know he's their dad.
where i'm from, all it takes to be popular is being pretty and/or rich. school sports teams aren't a thing like in america, so we don't have the whole athlete/cheerleader being the most popular kids in school, so it's a different dynamic.
i remember from primary school all the way to highschool, there were these twin girls, and no one made fun of them or bullied them, they were actually popular. so i don't think being twins would really contribute to the dolans being bullied. unless they were sherry and terry level of weird.
it's not exactly breaking news that youtubers always exaggerate stories and change facts to sell a certain narrative. so it's not unlikely they would exaggerate a thing or two, change a little thing here and there, just because that'd make a better video than the real stories