A longitudinal study of stressful life events assessed at interview with an epidemiological sample of adult twins: The basis of individual variation in event exposure

This study investigates the basis of individual variation in exposure to stressful life events (SLEs). A population based sample of 547 MZ and 390 DZ female-female twin pairs, aged between 17 and 55 years, were surveyed by two structured interviews, separated by at least 1 year, that enquired about SLEs experienced during the preceding 12 months. Data were analysed with a model that resolves occasion specific ('random') versus enduring ('stable') influences on SLEs. The latter is partitioned into that due to genetic, familial environmental and unique environmental factors. We demonstrate that both random factors and stable individual differences underlie variation in self-reported exposure to SLEs. For most network events this stable variance makes a relatively small contribution to the total variance in SLEs exposure and is almost entirely due to genetic or familial environmental effects. Stable individual differences are more important determinants of personal SLEs, and these reflect both familial factors as well as previous experiences unshared by relatives.