After several stressful events, depression was most likely among people carrying the short 5-HTT variant; with no stressful events, genotype groups differed little. Across all participants, more events predicted more depression.
Compare Caspi's interaction finding with the general stress-exposure finding.
40 exam-style questions on Edexcel GCSE Psychology 3.2 Studies, covering 3.2.1 Caspi et al. (2003) and 3.2.2 Young (2007). Each one has a worked solution and a mark scheme showing where the marks go.