I seduced my Mother

I'm Gary 21 single and live with my mother Cathy 39 divorced and my sister Fiona 19. Fiona and me were always mucking around and dare each to do things. I had been fucking her since she was 17 and it started because of one our dares. But we like fucking each other and kept it up. Last year during Easter after having sex, Fiona asked me I would fuck a more mature woman. I said Yes as long as she had a pulse. Then I want you to fuck a mature woman and you must seduce her not pay her for sex. What's in it for I asked. As many fucks as you can get for one thing she said. Not enough what else I enquired. Well if you fuck the woman I chose, I'll let you fuck my arse she answered. I've been trying to get her to let fuck her since we started fucking and she as always refused me. Alright, Who I asked. Our mother you must fuck her within 2 months or the deals off she said. Cathy our mother worked hard in the family business, which she inherited from her parents and never went out dating and I as far as we knew no sex life at all and doesn't drink at all. That a hard one, what else are you offering I said. Nothing else take it or leave it she replied. We can still have sex while I'm trying right I asked. Of course and look on the bright side if you seduce mom we might all be able to have a threesome she answered. I said I would need a week to work out my plan before starting the clock. She agreed and that how I started to plan the seduction of my mother Cathy. I start to hang around my mother more and watch her closely and I finally got my plan and it took almost 3 weeks. With the clock already running I started my plan and it was fairly simple. I would be around her more exercising and cuddling her more. As well as rubbing her feet, which she liked and as a child I didn't like doing. I was getting closer to her every day and even walked in on her in her bathroom while she naked. In the last week of the dare, I ramped up my game and one night while home alone with her I made my move. Cuddling close her and finally kissing her and she kissed back I move to feeling her up and started having sex with her on the lounge. After I had fucked her she was ashamed at what we had done and blamed herself. I told It was my fault and I had always wanted her and kissed again and started to fuck her again. Fiona came home and caught us fucking and while Cathy was still in shock at being caught. Fiona stripped off and wanted to join in with us, I kept fucking Cathy and then Fiona. We all slept together that night and after Cathy went to work next morning I cracked Fiona's arse. As a result Cathy has missed her period and was pregnant, I dared Fiona to go off the pill for 2 months and I got her pregnant as well. I'm still having sex with them both.