How do extenuating circumstances REALLY affect chances?

<p>I've seen some videos of admissions offices such as at Amherst College, and they seemed to be huge on anyone with tragic life sob-stories. Furthermore, how much of an impact does that really have on a student's admission? When I say tragic, I mean like the homeless-to-Harvard type of story where the parents were drug addicts, child suffers through tons of tragedy including loss of a parent, abuse, indigence, etc. </p>

<p>Thanks!</p>