It is well known to faculty members that the relatives of students tend to become ill and/or die much more frequently during exam and midterm season than at other times of the year. I was delighted to find a serious (?) statisitcal analysis of this phenomenon here:

http://www.math.toronto.edu/mpugh/DeadGrandmother.pdf

The data clearly indicate that the likelihood of a student’s relatives dying during exam time is strongly correlated with the student’s grade. One conclusion of this paper is that relatives of students worry themselves to death over their loved ones’ academic progress. The study recommends, among other things, that only orphans be allowed to attend universities. Unfortunately, the study is a bit out of date (1990), but I bet things haven’t changed much in the last twenty years.