Family Affair

Thirty plus years ago I had finished university and had started work in my career. I didn't have much family only a mother and younger sister, but that changed. Our mother got ill and quickly was gone, she and my sister worked at a local supermarket, and I sent what I could. Our plans were for me to get settled and they would come and join me. But only my sister could now join me, which she did straight the funeral. She returned with me, and I found a house and we lived together there until I had saved enough to buy our own home. We were now homeowners albeit with the bank, we had a plan. My sister worked at a supermarket and paid for the food and services; my wages went towards paying off the mortgage. We want it paid off asap and then we could enjoy ourselves. Neither of us dated and we didn't go out much at all except to work. I was getting pretty good money and also got bonuses, every spare penny went to paying off the house. But we're human and got sexual urges like everyone else. I used to masturbate and so did my sister and years after our mother's death we were almost homeowners and the bank paid off. The last payment made we celebrated and had a bit too much to drink. We got carried away and ended up fucking and took no precautions at all, might have not been a problem fucking just once. But three times was and of course my sister got pregnant straight away. After having every test going and no problems found she decided to have the baby. She started wearing our late mother's wedding ring and we pretended to be married. It was easier than I thought it would be, we hadn't been involved in the community before and as we were always together. Everyone had already assumed we were married anyway, with my sister pregnant and you can't get more pregnant we kept have sex together. Sharing the same bed, after the birth of our daughter, who we named after our mother. We kept having sex as before and almost 2 years later my sister got pregnant again. Now we are still together and have 5 children nothing wrong with any of them. My sister is very happy with our life and wouldn't change it she has said, nor would I.