In this study, we investigated whether different morphosyntactic features, i.e. number and gender, play a role during the adult online comprehension of subject relative clauses (SRC) and object relative clauses (ORC), in Italian. This study was inspired by developmental studies showing that children struggle with ORC compared to SRC; yet, ORC comprehension improves if the head and the subject of the RC mismatch in relevant morphosyntactic features (e.g. number but not gender in Italian, based on the featural Relativized Minimality principle, fRM). We found that Italian adults read ORC more slowly than SRC verbs; moreover, ORC verbs were read faster in the head-subject number mismatch condition, while there was no facilitation in the head-subject gender mismatch condition, in line with developmental studies and fRM. We conclude that online parsing is feature-sensitive, that features are not all equally “relevant”, and that current models should be refined to account for these differences.