Is it normal to imagine your sister while watching incest porn/hentai

When i watch incest porn or hentai, at some point i start to think of my elder sister n then again focus again on the porn n then again same imagination and when i masturbate afterwards thinking of it again her thought comes into my mind. How to divert myself? Edited: no diversion needed. This is what i want to love her as a woman. Reminded me of the days when i use to feel her assets in her sleep.