Is it weird that I get aroused while listening to my parents making love?

Hi. I am a 16-year-old female and my parents are both 36 so they are not like super old or anything. I hear them having sex every weekend and sometimes during the week. The weird thing is, I don't just hear them, but I find myself listening in and get very aroused by the sounds and masturbate. I actually stay up in my room after going to bed at night so I can listen to it. Also, I sometimes deliberately go to bed early when I hear the change in my mum's voice she gets when she wants to have sex and do this so they then feel free to go to bed themselves and start having sex while I can listen in without having to stay up so late. Growing up, my dad has never been comfortable having sex while I'm still awake and might hear them and my mum has never liked having to wait for sex when she's turned on. When I was younger, she would often go upstairs and have a shower after dinner and then come back downstairs wearing just a satin robe and I'd notice a change in her voice as she found an excuse to send me to bed early. She would then get my dad to take her to bed and would want him to have sex with her straight away, but he would be hesitant, saying I might still be awake and could hear them. My mum would just say that she'll keep her mouth closed and try not to make too much noise. That never lasted long, though. I would hear my mum make a little wincing noise and then start breathing heavily and moaning, but as the intensity built, it wouldn't be long before it all started becoming too much for her and I would get very turned on hearing the desperation in her voice as she struggled to contain her sounds. Just hearing the sheer pleasure and intensity of it would always get me so wet and I couldn't help but start rubbing and fingering myself as I needed a release from getting so worked up. I think the fact that I was hearing something I wasn't supposed to also added to the excitment, like it was naughty and taboo or something. I don't know, but I have enjoyed listening to them having sex ever since. Is it weird that I get so turned on by this and don't even care that it's my own parents? Has anyone else had this reaction when they've heard their parents having sex? Oh and before anyone asks, I have absolutely no desire to join them or anything creepy like that, so don't even go there. I just can't help but get aroused when I hear them having sex at night and need to know if this is normal or not.