Normally, one could think that children in their early years still eat everything because they have not been able to develop any aversions or refuse one or the other food due to traumatic eating experiences. But that is only half the truth. True to the saying "What the farmer doesn't know, he doesn't eat!" many children also act. However, this fear or aversion to new and previously unknown foods does not have to be.
By the way: Adults also eat too few vegetables for the most part, so that all "non-parents" are now welcome to listen.
One origin of this avoidance can be seen in the taste of the food. This makes many vegetables taste slightly bitter. Normally a bitter taste in nature means something poisonous rather than something healthy. So, you could almost think that our lust for sweets - which is rarely poisonous - somehow ensures our survival... If it weren't for all the vitamins in the countless vegetables...