Is it normal to have sex with my cousin?

When I was 15 and my cousin was 15, I used to get really turned on by my sexy cousin. She would always tease me in ways that shouldn't have gotten me hard but did. Sometimes, just so I could jack off later, I would jokingly slap her ass. On my sister's birthday, my family went out to order food, and it was just my cousin and me at home. We had to take the dog outside on a walk. When we came back, she noticed me staring at her beautiful ass. She told me she was going to take a really short quick shower because she got dirty outside. I let her use my bathroom and shower. I needed to get something from my room, so when I heard her turn the shower off, I walked in. I saw her in my bathroom, naked, blow-drying her hair. She had beautiful tits and an amazing ass. I saw her and immediately got hard. She noticed me in the mirror watching her. Like she didn't even care that she was naked, she saw my hard dick and walked over to me. She asked me if I wanted to touch her, so I rubbed her tits and her pussy. She held my hand at her pussy and wanted me to keep rubbing. She pushed me onto the bed, took off my pants, and rubbed my dick. She jacked my dick and I came all over her face, in her mouth, and on her tits. After that day, she continued to jerk my dick until we graduated.