I think like many interview questions, this is one of that has no "right" or "wrong" answer, except that it would be a good idea to keep the answer succinct, with a natural flow. I would frame an answer in the context of upbringing/background, educational/vocational experiences, and personality traits. Maybe I would take a minute to say where I am from and have lived, then a few minutes on what my passions are and where I would like be professionally/academically in the near future, and another few minutes on how my experiences have shaped the way I think and operate (in the relevant context of the position). The interviewer(s) will probably ask your further questions based on your answer.