"Don't just tell him, Jake," Christy said. "Let's show him."
Jake turned from his father to face Christy.
She immediately began stripping. Within seconds she was naked, flaunting her fuckability.
"See what I mean, Dad?" Jake sighed. "Look at her. I'm only human."
"Amen!" Christy crowed. After sinking to her knees, she yanked Jake's jeans down to unleash his jutting hard-on.
In his last shrugging statement to his father, Jake said, "What can I do? Gotta fuck her."
On cue, Christy spread herself at her cousin's feet, as close to all-cunt as a girl could get. As fast as he could get there, Jake was rocking in the cradle of her thighs and shafting her teenaged cunt with his teenaged cock.
Which left Luke and Helen. He still hadn't quite made up his mind, but she was too important to keep waiting. She bowled him over. Then, when he was flat on his back, she straddled him with her thighs. And, sliding her cunt down his cock, she all but began raping him.
"Well?" Helen asked, when her dripping cunt had captured Luke's hard-on.
"I'm only human." Luke repeated his son's words with acceptance of his fate. Then his thrusting cock did the rest of his talking, as he started fucking back.
And so the last stop on the Conway's summer vacation completed the spiraling circle of family sex. It had started with Christy almost innocently losing her cherry to her country cousin Jake, only to lead within two short weeks to cross-country incest. As the cause of it all, Christy climaxed with pride, her cousin's cock in her cunt, while looking forward to what next summer would bring.