I’ve always thought that 2D having blue hair was a puberty thing where it began growing in blue naturally when he started to go through adolescence, and that’s why his kiddies are described as having naturally blue hair as well
In childhood he fell out of a tree and got a nasty concussion that made every bit of his hair fall out and grow back blue, so I guess the implication is that the concussion changed his DNA… That’s actually when his crippling head aches started and he got on prescription pain meds, not because of the car crashes.














