When Frank saw his sister in the kitchen cleaning up he went up to her rubbing his cock up against her ass and grabbing her breasts.
"Not now, Jim, the kids may see us!"
Frank let go of her breasts and stepped back quickly. They weren't his sister's breasts he had just grabbed. They were his mother's. "Oh fuck, Mom, I'm sorry. I thought you were Gail."
Jean just stood there looking at Frank's throbbing cock.
Frank's sister, Gail, started laughing when he told her about trying to fuck their mother. She got a mischievous look on her face and said, "I wonder if Dad would fall for the same thing. I look just like Mom and we even have the same haircut."
They came up with a plan... Their father plays golf every Saturday. All they needed to do was get their mother out of the house. Frank convinced her to take his car and go shopping.
When Jim got home from playing golf Gail was standing at the kitchen sink wearing panties and one of her mother's tee shirts. When he saw Jean standing at the sink in her panties he unzipped his pants letting out his growing penis. Tip-toeing up to Jean he pulled her panties down and pushed his hard cock between her legs.
Without turning around Gail stepped back and bent over the sink spreading her legs a little to give the expected cock better access. Reaching between her legs she grabbed her father's cock and guided it to her pussy where he buried it all the way to his balls before pumping it in and out.
After her father finished unloading all his cum in her pussy Gail stood up and turned around. She feigned total surprise and started apologizing profusely. "Oh, Daddy, I'm so sorry. I thought you were Frank. Will you ever forgive me?"
Jim was flabbergasted. He had just fucked his daughter. "No, I'm to blame. I thought you were Mom."
Gail saw a small drop of cum at the tip of her father's cock. She reached down and squeezed the last bit of cum out of his cock catching it with her fingers.
She looked up at her father and stuck her fingers in her mouth. "I won't tell anyone if you don't." She pulled her panties up and went back to her bedroom.
Jim's dick was getting hard again as he watched his daughter go.
Later that afternoon Frank and Gail got home from an early movie and saw their mother and father lounging in the sun by the pool. Not wanting to disturb them they stood in the kitchen watching.