have a mind of your own
have a mind of your own1 be capable of independent opinion or action. 2 (of an inanimate object) seem capable of thought and desire, especially by behaving contrary to the will of the person using it.
have a mind of your ˈown
1 (of people) have your own opinion and make your own decisions without being influenced by other people: She certainly doesn’t need your advice; she’s got a mind of her own, that girl.
2 (humorous) (of machines, etc.) behave in a way that you do not expect: This photocopier has a mind of its own. If I ask for ten copies it does one; if I ask for five, it does fifteen.