The basic premise that children must learn about emotions is that all feelings are okay to have; however, only some reactions are okay.
But the rational mind usually doesn't decide what emotions we "should" have !
Fear, in evolution, has a special prominence: perhaps more than any other emotion it is crucial for survival.
For better or worse, intelligence can come to nothing when emotions hold sway.
Like secondhand smoke, the leakage of emotions can make a bystander an innocent casualty of someone else's toxic state.