Stepbrother caught wanking

As I don't have a driving licence but had to go shopping, I went to my stepbrother's so that he could drive with me. When I came into the living room, he was sitting there with his mobile phone in one hand and his cock in the other, wanking himself. Oh man, he was pretty embarrassed. But since I've always liked him, I quickly defused the situation and took my chance to finally fuck him. Why didn't I do that much earlier? Have you ever had sex with someone from the "family"?