Do you think my cousin hate me?

my cousin's parents died in a car accident about three years ago, so she lived with our uncle for awhile, but then she moved in with us. i'm 20 years old, and she's 16. she's been living with us since early last year, and she keeps building onto our house, like the GIGANTIC two story clubhouse-looking thing she built next to our house, connecting to her bedroom(she calls it her lab, but i call it her lair). she hates when people go into her room, she almost always keeps her light off, and on occasion when i do manage to see her room, it's always really messy with her books, clothes, tools, etc. lying around everywhere. we probably argue more than anyone else that lives here, which is pretty weird, because besides our personalities, hobbies, and opinions, we have a lot in common with each other. but we rarely agree on anything, we call each other names like dragon(my name for her) and cretin(her name for me), and we overall don't get along very well. she's always so cold to me, so i naturally respond in a similar way. why do you think she does it? does she hate me or something?