Overlap is expected as the composite indices (SRED, SRRD, and SRHD) make up the total SRE score SRTT, making it difficult to tease out the significant heritability of SRTT without considering the individual indices. SRED was lower than SRRD which in turn was lower than SRHD, showing a progressive increase in alcohol consumption and a consequent decrease in level of response. A significant heritability of SRTT could then indicate that the total score is not only heritable, but indicative of a progression to lower LR with time, in this sample.
