Beef carcasses from F2 Nellore × Angus (n = 181) and half-blood Bos indicus × Bos taurus (n = 57) were used to evaluate the responsiveness of sire and family groups nested within sires to post-mortem electrical stimulation (ES). In the F2 population, biological response to ES was identified for myofibrillar fragmentation index, and 6 h post-mortem pH. The genetic contributions of sire and families nested within sires were found for the average Warner-Bratzler shear force (WBS), location of shear core extraction, post-mortem carcass temperatures, and carcass pH. ES sides had lower WBS values, higher carcass temperatures, and lower carcass pH. In the half-blood population, biological response to ES was found for WBS core location. Sire and families nested within sires significantly affected WBS core location and carcass temperature. The ES sides had lower WBS values, higher carcass temperatures, and lower carcass pH in the half-blood population. From a carcass temperature and pH standpoint, carcass weight and fat thickness were used as covariates in the analysis of variance. This covariate analysis still showed a genetic component to carcass temperature and pH. There are genetic factors that impact how carcasses respond to electrical stimulation, which is the first work to demonstrate this relationship between genetics and a post-mortem tenderization treatment.