And it's not just stubbornness...
Getting children to eat their greens can be a struggle.
But even as we get older some of us just aren't quite game for a big plate of the healthy stuff.
Well, turns out it may be more than just not liking the taste.
For kids anyway... so we're not all off the hook!
Researchers think they've discovered why children dislike broccoli and brussels sprouts.
Their research suggests enzymes from these vegetables and from bacteria in saliva can produce unpleasant odours in the mouth.
And apparently we learn to tolerate the odours as we grow up.
That's why adults can (mostly) enjoy vegetables like kale and cabbage.
What we've learned is it's all down to your spit - how lovely.
They've found that kids whose spit produced the most smelly compounds show the strongest dislike for the green veg, compared with adults and their peers.
Another finding from the study was that cauliflower actually gave out more of these smelly compounds - so it's not just confined to greens.
The new study was published in the Journal of Agricultural and Food Chemistry.
