If you're a large male, especially if you sport a beard, you will probably experience that smaller children react to you with shyness or fear quite often. I have seen children crying when a young men entered their car. The small kid hiding behind their mother's legs is a stereotype born from real-life experiences.
But the behavior often completely changes when that male person is accompanied by another child that isn't shy around them (e.g., their daughter). Apparently, there's a deep-rooted instinct in children that tells them "this one is a father and thus cannot be a bad person".