What does having a mature mind mean?

my therapist told me that i have a mature mind compared to her other clients that are around my age (i am 16). however, my parents ALWAYS tell me to act more mature though. does it mean i am intelligent? i don't think i am so smart even though some of my first cousins are scientists and my sis was magna *** laude ; my parents both agree that i am a very smart, lazy child.