Is masturbation unnatural?

I wanted to ask a question about masturbation. Is masturbating unnatural or weird? Recently, my mother has caught me masturbating (I am male btw.) And she got very angry with me and called me many names. The next day, I avoided her as much as I could and spoke very little to her. Later that same day, she came to me telling me that she better not ever catch me doing that again. I responded saying that she acts as if masturbation is unnatural and she replied that it is. She has caught me other times too and acted the same way each time. The simple solution would be to go somewhere private and lock the door but the problem is that my mother will not allow me to ever lock my doors or just be by myself for long periods of times. She never knocks and just walks right into my room. I don’t understand why she thinks masturbation is unnatural either. She is a Christian and she does try to force her thoughts or beliefs onto other people rather than accept that people have different views.