the correlations between religiosity and problem alcohol use were −0.15 (adolescence) and −0.13 (young adulthood). Correlations of the twin-pair differences for religiosity and alcohol problem use provide a within-family replication of the between-family correlations described above. That is, we analyzed the data to determine whether the twins who scored higher on religiosity than their co-twin also scored lower than their co-twin on alcohol problem use. Results were largely comparable to the between-family scores, and importantly, were also negative; for males, the correlations were −0.03 (non-significant) in adolescence and −0.11 (significant at the 0.05 level) in young adulthood. For females, the correlations were −0.13 (significant at the 0.01 level) in adolescence and −0.11 (significant at the 0.05 level) in young adulthood.
