[Even if she had told him that he acts weird, he would've been confused. He doesn't know how other 15 year olds act. He stares at her for a moment, thinking. He doesn't want to pry, so he bites his lip before asking]
How old are you? Y-You don't have to answer if you don't want to.
[action]
How old are you? Y-You don't have to answer if you don't want to.