get into my things

Dear teachers.
I'd like to know the meaning of "getting into my things" in the next story.

Dad, she's in my room getting into my things again!"
"Mom, he won't stop looking out of my window!"
"Me first! Me first! Me first!"
Do any of these statements sound familiar? If you have more than one child, they probably do because these are all common examples of sibling rivalry or sibling conflict.

[Mister Micawber]

'Getting into my things' = touching/utilizing/investigating my personal possessions.