mind of one's own, have a

have a mind of (one's)/its own

To have the propensity or ability to think, act, or form opinions without outside influence. It is often used (humorously) to describe an inanimate object that cannot be controlled by its owner. I tried to tell him that wasn't the best decision to make under those circumstances, but you know he has a mind of his own, and he did it anyway. I swear, my vacuum has a mind of its own! It turns on in the middle of the night when we're all asleep!
See also: have, mind, of, own

mind of one's own, have a

Think independently, reach one's own opinions or conclusions. For example, You can't tell Karen what she should wear-she has a mind of her own. Also see know one's own mind.
See also: have, mind, of