They sent me a brochure of prospective nannies and as I leafed through it I came across a startling beautiful 18-year old that had me instantly mesmer...ized and I must admit, instantly erect. Her name was Keisha and from her pics she appeared to be about 5 feet tall and weighed about 100 pounds. She had jet black hair that went down to her ass with porcelain white skin. I called the agency and set up a meeting to meet her the next day. The following day we met and she was even smaller than I. " What are you scared about?" Well the guys at school are starting to get big and hairy and muscularand their voices are breaking." Don't worry son, you will start growing, you will soon be a big strongman like them." But I don't want to be a man." What do you mean, do you want to be a dog or a horse, don't be silly." No, I want to be a girl." Don't be daft you are a boy. Wherever did you get that dumb idea?" I have wanted to be a girl for ever. I hate being a boy." Just because you are a bit. I helped her get comfortable in bed and pulled up the covers and kissed her forehead. I did note that, much as I had thought, her breasts didn’t sag very much, at least not until she lay down, then they lay flat onto her chest. Still when I turned and left the room my face was crimson with embarrassment, not because I had seen my mother naked but because I had an obvious erection.With mother safely tucked into bed I went back downstairs and into my father’s study. I cleaned up the mess mother. However I reach out put a hand on her head and force to take more of my stiff prick in her mouth, down her throat. Melissa gagged on my cock as I shoot my load down her throat. Cum fills her mouth and dribbles down her chin.I get up and tuck my semi hard erection back in my pyjamas and walk away. Leaving the horny 18 year old with her hand between her legs."Where are you going?" She asks "Bed!" I reply "Good idea" she says getting up and follows me.I am lying on top of duvet, my wife sound.