I probably shouldn't be criticizing someone else's parenting, but there is a boy in the Pumpkin Princess's class at day care with red hair. Not nice auburn hair, or carrot top red, or even strawberry blond. (BTW, the kid looks like a full-bloodded, run of the mill Japanese, or at the very least, 100% East Asian, so none of these colors would be natural.) No, I'm talking anime character bright red with a shade of pink. To get Asian hair that color, it has to be bleached before it gets dyed. To think that the kid's parents (or maybe only one parent was involved in the procedure, but I'm pretty sure it was a parent because no hairdresser in their right mind would take part in anything so dangerous) applied two different potentially hazardous chemical substances on a 4 year-old's scalp (or more importantly, so close to the eye area) is in itself cringe worthy, even if they hadn't picked anime character red as the final color.
And even though you managed to get the desired look without corneal damage, using hair dyes on very young children increases the risk of their developing a hair color allergy later in life. The worst case scenario would be, if the kid actually likes the look and decides to repeat it when he is old enough to decide for himself, he'll get contact dermatitis, or worse, an anaphylactic reaction every time he retouches his roots.