Anyhow IMO vegetables are a supercharged form of hormetic stress. I don't think it's as important for children to ramp this up as it is to just avoid what we can in known environmental toxic stress. I believe there is a legitimate reason children gravitate toward sweet items and avoid the "bitters" early in life. And no, I don't think this is just cause they were not introduced to bitter greens earlier. Bitters are indicative of those hormetic stressors/toxins in that food... as we age it seems our palate expands to actually enjoy this. As a young child not so much.
But here ... just found Marks take on it:
Dear Mark: Obesogens, Tots Who Hate Veggies, and Pregnancy Recovery | Mark's Daily Apple