Children with specific language impairment (SLI) often have a family history of language disorder. In this study, ERPs in response to a visual semantic priming task were recorded in parents of children with SLI. Despite equal performance, the ERPs displayed differences in language processing: larger N400 amplitudes indicated that the parents, especially the fathers, were less primed by the preceding context. Difference waveforms showed that the fathers of SLI children, contrary to controls, had less differentiated responses to congruent versus incongruent sentences. We propose that the N400 observations may be residual markers of past language deficiencies in the fathers. No differences in the N400 effect were found in the mothers of SLI children.