Seeded my sister

Both my sister (25) and I (27) were getting over broken relationships, neither of us were in a hurry to start another relationship. So, we hung out together and seen a couple of movies together and attended a family wedding together. Stayed in the same hotel room and after the wedding reception in the same hotel. We headed for our room, both fairly drunk and I can't remember how we started, but we started fucking. Fucked again in the morning and still fucked again later in the day. On returning home, we became regular lovers and, on my sister, finding out she was pregnant. Well, what could we do but live together and as our departed father had departed 20 years earlier, we only had to tell our mother (47) about our sexual relationship and her first grandson's fathering. Which she took better than we both expected. We move back in with our mother, and she has joined in our family affair. Extended family didn't asked, and we didn't say.