Mom was panting from the effort of swimming the length of the pool. I guess too much wine and too little exercise must be hard on the body.“You kids...go ahead and have fun. I’m just going to rest a while. Ok?” Her essentially naked ass looked very inviting as she climbed out of the water.“Ok, Mom. You just relax. Mary and I will stay in a bit longer, then we will join you.”Mary and I were joining even as I spoke. I glanced over to see if Mom could see us, but her head was turned the other way. I would be on my own tomorrow, for at least part of the day, but she would make Maria available if I wanted to go anywhere, and I only needed to ask Olivia if I wanted something at the house.After hugging and chatting for a few minutes, Linda led me to an open air sitting room that also overlooked the water. Through the foliage, I could just barely make out the walls of the part of the building I assumed was where my room was located. We sat down on a porch swing that was just out of the sun. But right now, my need was overwhelming; the events of the afternoon had woken something that had been asleep for far too long, and could not be put back in its box.I moved one hand down to my cunt. My pussy lips were clearly visible through the soaking material of my panties. I gently ran my fingers over them. I felt another shock as I did so, and another moan escaped my lips.I eased my hand inside the top of my knickers, enjoying the feel of my pubic hair. I slipped a finger into my crevice,. “I don’t know, it seems kind of weird since you are my s****r.” “No one is going to know and besides I can tell you want me too as much as I want to.” I really did want her to touch my cock. In fact I wanted more. I wanted to touch her all over and fuck her so bad it made my balls ache. I didn’t say anything else. I really didn’t need to she went straight for my shorts and started to stroke my hard on. It felt great. I relaxed and laid back on the bed to let her stroke as much as she wanted to..