Why does my eyes change colors? and what is it called?

My eyes change during the day. They can be any color, u name it. My pupil is also surrounded by a thin line of yellow. They seem to change to my surroundings. Like what i’m wearing or what im around. i doubt they change with my mood because i would have noticed it. plz help me know why my eyes have always been this way.
Also everyone in my family has dark brown eyes. And I was born with dark blue.