Sounds a little odd. If my mom mentioned piss test at anytime since I started toking 13 years ago I would have had to have been seriously deranged. I was asked on the first night I toked what I had been smoking, I stoopidly said "why? what can you smell". That reply didn't land me in any bother. It was many years later; after going out early and coming in late stoned every night for months, my dad sat me down and told me to look at myself and how stoned I was and asked probing questions about what I wanted to do with my life and how much I was being disrespectful by having a cannbis habbit. Then he asked me if I sold weed. I didn't answer. He knew it was a yes. I think he found out because I was really careless. I'd bag my shit up at my mates house in front of his rents, I'm sure they mentioned it to my dad. At that point my smoking cover was blown. The reality is if you want to do stuff and get away with it you have to be 2 steps in front of everyone who you want to keep out of your personal life. Failing that, we all have to put up with the opinions of others when we involve them in our business.
Stop arguing and having bust ups. It takes two people to argue and fueling the fire when you don't wish to feel the heat is not a good idea. I am a private person in front of my rents. If they ever knew how much weed I cultivate annually they would have far too much to say regardless of me living in my own place or not. But so long as I show them signs that I am healthy and keeping out of trouble then they can only assume that I am doing good. Was that shyt?