When you hit puberty, your breasts grow larger (if you are a girl) and your hips more curvy and wide. For boys, they generally become more masculine and tall.
Not necessarily. He may just be a masculine boy.
Many of them you just have to memorize. As you practice more, you will become more familiar with what words are masculine and feminine, and it will become second nature to you. The Related link below has some helpful hints on the subject.
no usually when you have a growth spurt you become more fit developing height and becoming more masculine
A girl can become more busty by becoming more arrogant and bold. In addition, her attitude and personality will have to be more confident. She will have to dress differently, too.
When a girl says you have girly lips, it means she thinks your lips are more feminine looking than masculine looking. This is just her opinion.
Talk to her more, become her friend and see what happens from there
feminine la fille
amigo - boy amiga- girl
Shadow can be used as a girl's name, though it is more commonly associated with a gender-neutral or masculine connotation. Names like Shadow provide a sense of uniqueness and individuality regardless of gender associations.
The word "enfant" is both a masculine and a feminine in French, so you can write "un enfant" for a boy (or even a girl) or "une enfant" (for a girl only). The plural "les enfants" could be both feminine and masculine, but it is very likely that the vast majority of French speakers understand it as masculine, the masculine being also the mode you use in French when being "unspecific" about the gender.
You really can't. It's more of a born quality