Covid started it

In 2020 I 37 was unattached living on my small farm 120 acres, growing a range of different things for the nearby city. Have my own water supply, wind and solar power to power my farm. Off the grid mainly because of the cost of the power company running a powerline to my farm would cost over 200 thousand dollars. My access road is maintained by me, just grade it twice a year and it lasts fairly. The ground is well drained naturally and so rain doesn't turn it to mud. So, living alone and then Covid started to make the news. My older sister 40 (only sibling) divorced one child a daughter 21, decided the city wouldn't be safe for either of them. Our parents both deceased from cancer for my father and heart attack took our mother. Both my sister and niece working low paid jobs were just getting by and couldn't afford to miss even one day pay. So, when talk of a lockdown started, they both came to stay with me until the everything went back to normal. But they never expected it to last very long a couple of weeks a month at the most. But as it dragged out, we just looked after the farm and wondered how long it would last. I started reading my porn mags in the barn and masturbating myself. I got caught by my niece who got horny seeing my erect cock. One thing led to another and we became lovers, no condoms available so we used the pull-out method. It was working quite well, well until we were caught by my sister fucking. In the shock of getting caught I failed to pull out in time. After my sister calmed down, it turned out she was more upset over her being left out more than us actually fucking. So, no hiding away in the barn sex was now in the house with just one of them at a time or both at the same time. Still using the pull-out method. Several mistakes were made with both, but we never worried much about them. Finally, after months of isolation the lockdown ended, but we still stayed isolated longer just in case as they say. We finally had to go and get vaccinated and my niece got a pregnancy test kit, first I knew there was a problem. My sister also got a test kit, but neither actually thought they were pregnant. But both with positive results changed our plans quite a bit. So now I've two sons and a daughter, a son 3 by my sister and a son 3 and daughter 1 by my niece, all healthily. We still live together, still fuck and still use the pull-out method. Why change we're all happy with the results as is.