I wish to know why

[wayfaringwordhack]

...toddler boys who throw tantrums are said to be "strong-willed,"* and why if a little girl exerts her personality, she is thought to be capricious.  

The first implies that, yes, the boy can be stubborn; he can hold on to what he thinks is right, all the while acting like a terror. A strong will denotes reasoning power on the part of the "afflicted."

Capriciousness, however, lacks reason. It is irrational. It is whimsy at its worst, stripped anything fanciful or flattering.

Are there other similarly biased adjectives to describe boys and girls in English or other languages?

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* used in French, strong-willed can be a two-edged sword, a compliment as well as a deprecation.  However, when I've heard it used by parents to excuse their children (boys), it is with a touch of pride, concealed but there all the same. Capricious is always, as far as I can determine, negative.