Sent to live with Grandma

I was 18 and a handful for my widowed mother, she was trying care for my 2 younger siblings and work to support us. I worked off and on, being a high school dropout, I wasn't working high paying jobs. Casual jobs called when I was wanted and no pay if not required, finally my mother sent me to her widowed mother 61. Telling me there was more work near grandma's home then in our area. I went and got work straight away and it was almost fulltime, but I became fulltime after a few months. Earning more money than ever, I started to have money right thru from one payday to the next payday. Before I was out of cash 5 days after getting paid. Also, I was able to get extra work, paying cash in hand and thought I was on top of the world. Not a great Ladie's man due to being broke all the time, I hadn't dated. So, of course I masturbated to get off and I was caught masturbating by my grandma. Who was shocked at first, just because it unexpected by her at the time. Quickly recovering she decided to take over stroking my cock and quickly got me off. Turned out she masturbated regularly herself and now she had a horny young man almost 19 living with her. She asked me would I like to fuck her, and I said Yes, and we became regular lovers. Not that we are anything special in looks, both overweight and on the plain side in looks. With me earning better money I wasn't thinking of returning to my mother and siblings anytime soon. But they came to join us as my mother lost her job due to the company closing down. My siblings (15 and 12) were doing okay at school unlike I had and now the 5 of us were all living together with grandma. Sex with grandma wasn't interrupted as my mother worked days in her new job and my siblings were at school, I worked nights and grandma work early shift finishing at 10. So, I got home at 6 30 and had some sleep grandma got home 10 15 and we would shower together and have sex and then she would cook dinner and I got some sleep before my next shift. My siblings got home an hour before mother, and we all had dinner before I went to work. That's how it is now and I'm turning 20 next month. School holiday my sibling's work to make some money and that allow me and grandma to continue having sex on a fairly regular basis.