People vary in the occurrence and perceived severity of stressors experienced in their daily lives. In the current study, the authors examined the extent to which individual differences in these relatively minor occurrences are determined by genetic endowment as well as environmental influences and how these effects vary by age. Identical (n-sub(pairs) = 111) and fraternal (n-sub(pairs) = 99) twin adults ranging from 25 to 73 years old reported the occurrence and severity of their daily stressors on 8 consecutive evenings. Both genetic and unique environmental effects accounted for the variance in stressor occurrence, whereas shared family and unique environmental effects accounted for the variance in the perceived severity of these stressors. In addition, the influence of unique environment on perceived stress exerted a stronger influence among the older adults than the younger adults.
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