After Thanos' invasion, the Terrigen Mists were spread all over the surface of Earth, activating the latent powers of numerous Inhuman descendants. Rob and the rest of his family, except Vic, suffered from Terrigenesis. After Vic called the police when Rob and the rest of the family were enclosed in cocoons, they were transferred to an Inhuman Nativity Center.
Vic grew resentful, thinking that he didn't suffer from Terrigenesis because he was adopted. When he acquired the Nightbringer Mandarin's Ring, he went drunk to the Inhuman Nativity Center and attacked it, accidentally killing his father in the process.
Victor later suffered from Terrigenesis, and it was revealed he hadn't suffered from it earlier because the level of exposure to Terrigen Mists necessary to trigger the Terrigenesis can vary from individual to individual, and not because he didn't have blood ties with his family.