Abnormal thoughts..please help

At age 7 i began to have thoughts involving kidnapping, humiliation and sometimes urination. I have never been abused etc and it scares me to think that these are the first thoughts that led me to feel what i now recognise as arousal. This could have first came about just as imagining getting kidnapped etc like kids do and then the idea of being nude etc came in and as i said made me feel what i now recognise as arousel. I have loving parents and have always had a happy life and i have lots of mates and a completely normal social life. I just dont understand why these things came into mind and it disturbes me to know that these were my first arousing thoughts. I am now 15 and any fantasies i have are completely normal. please help me understand.

It is normal to have abnormal thoughts to get aroused, as long as you keep them to yourself and do not act upon them.