Is masturbation a sin? What evidence supports that?

So, I was talking to my parents for like an hour. I think masturbating is a sin. They don't. They brought up some points that you can't really disprove like it not being in the Bible and people being less angry( talking about my brother) when they do it. I brought up sexual immorality but they shut it down by saying masturbation isn't immoral. Is there any concrete evidence or anything? Why do you guys think masturbating is a sin or not a sin?

I appreciate the responses, thank you everyone!