My thoughts are that 'you' as a person change constantly, year to year, and who you are now is not the same as 5, 10, more years ago. I don't think it's so much that you are a different person because you lost a limb or are drunk, it's the change in personality and mind that accompany those that makes that person different. You could absolutely lose a limb and be 'the same' person, but you could also change significantly.