Parent sex ratio allocation has consequences for individual fitness, population dynamics, and conservation. Theory predicts that parents should adjust offspring sex ratio when the fitness returns of producing male or female offspring varies. Previous studies have assumed that only mothers are capable of biasing offspring sex ratios, and neglected fathers given the expectation of an equal proportion of X- and Y-chromosome bearing sperm (CBS) in ejaculates due to sex chromosomes segregation at meiosis. This assumption has been recently refuted and both paternal fertility and paternal genetic quality have been shown to bias sex ratios. Here we test, simultaneously, the relative contribution of paternal, maternal and individual genetic quality, as measured by inbreeding, on the probability of being born a son or a daughter, using pedigree and life-long offspring sex ratio data for the eastern bongo (Tragelaphus eurycerus isaaci). Our models showed firstly that surprisingly as individual inbreeding decreases the probability of being male increases, second, that paternal genetic effects on sex ratio were stronger than maternal genetic effects (which were absent). Furthermore, paternal effects were opposite in sign to those predicted; father inbreeding increases the probability of having sons. Previous paternal effects have been interpreted as adaptive due to sex-specific inbreeding depression for reproductive traits. We argue that in the eastern bongo, the opposite sign of the paternal effect on sex ratios results from a reversed sex-specific inbreeding depression pattern (present for female but not male reproductive traits). We anticipate that this research will help stimulate research on evolutionary constraints to sex ratios. Finally, the results open a new avenue of research to predict sex ratio allocation in an applied conservation context.