Moreover, grandmothers of students who aren't doing so well in class are at even higher risk - students who are failing are fifty times more likely to lose a grandmother compared with non-failing students. In a paper exploring this sad connection, Adam speculates that the phenomenon is due to intrafamilial dynamics, which is to say, students' grandmothers care so much about their grandchildren that they worry themselves to death over the outcome of exams.
~ Dan Ariely