Neglected Mother

My father married my mother because was gorgeous, she was 19 and he 31 had 3 children together me plus older sister and brother. I'm the runt according to my father and brother, my sister is nicer and so I prefer her to my annoying brother. I was born when my mother 26 and I'm now 18 solid build and short at 5'3" I will go to university unlike my brother and father. My father now 57 and ignores my mother, playing golf and telling everyone he is a self-made man. But he inherited everything, and the value only went because he wasn't running the business his late father saw to that. My sister still lives at home and doesn't do much, doesn't date and has an online advice service. But it keeps her happy that's the main thing. I was caught cock in hand by my mother and being the great mother she is, she got me off. I'm not the greatest with girls and my sexual act at the time was my mother getting me off. My mother is happiest when my father is playing golf or away somewhere, they have separate bedrooms on opposite sides of the house. Anyhow as my mother now knew I masturbated; I wasn't so tense when masturbating. She even suggested I do in the shower and so no cum on the sheets. She doesn't do the washing, but it would stop the servant's gossiping about it. Anyway, one Sunday afternoon I was horny and going to shower and as I passed my mother, she what I was doing. I said going for a shower and she asked did I what a hand. I looked at her and said always, she got up and we showered together, and she got me off again. After showering as she dried herself, I got another hard-on. She saw and took me to my bed and fucked me, I left all me cum inside her. I was a bit concerned as I thought she might get pregnant, but she said she can't have any more children due to surgery. My mother had decided seeing my second hard-on to stop acting like a nun and enjoy herself. I don't masturbate much at all now, I just look at my mother and she smile back, and we have sex, or she looks away and we don't. But our secret sexual relationship, didn't unnoticed my sister saw us together quite a lot and then caught in the act. But she just wanted to join in, especially with our mother. My sister is bi-sexual and prefer women more than men and our mother was her dream partner, a dream no more. I got carried away fucking my sister's pussy while was licking our mothers and left me cum in her and so she is 7 months pregnant, and our father usual take no interests. Our brother likewise neither has picked up on our mother, daughter and youngest son's interplay. Even my sister sleeps most night in mother's bed with and me. Father doesn't care his daughter is pregnant and hasn't asked by who even. Mother is very happy with the pregnancy and the healthy granddaughter she will soon have. As for me I want to keep fucking my mother and breeding my sister, my sister said she'll see how the first baby goes before agreeing to another.