You don't know
From Torg Adventure
You don't know if you're sterile or not. As a couple, your wife and you hadn't had any luck having more children, but you'd never looked into why. You had even tried to have another as recently as five years ago with no luck. You were just thinking about getting tested, when your wife died in a car accident. But you really don't know why.
But the possibility that you're sterile is enough, your blood-starved brain rationalizes, and you don't say anything to Kim.
You roll off of your beautiful daughter. She cuddles into your body, wrapping her leg and arm around you and laying her head on your shoulder. In barely a minute, she is playing with your nipple and then fondling your limp cock. She raises herself up and kisses you hard on the lips. Her tongue enters your mouth unbidden, but you flick your tongue across hers, enjoying her taste. You make out wildly while she's rubs your shaft into stiffness.
She breaks the kiss to say, "Can you always get hard three times in a row, Daddy? I read in Sex Ed. that it often takes an hour for the man to get hard again."
"You're so hot, baby, I get hard fast." She blushes at the compliment, something that makes her even sexier than before. The redness under her pale skin makes your blood boil. Somehow, your cock gets harder still.
"Well, if you're sterile, there's no harm in going again, is there?" With that statement, Kim swings her leg over your waist and straddles your belly. Your steel-hard shaft is wedged between her ass cheeks. You look up and marvel at the sexy beauty of your daughter. Her tits sit way up high, round luscious orbs topped with fat crinkled nipples. Her flat belly undulates as she rocks above you. Her trimmed blonde bush is split by her thick swollen pussy lips, which are dribbling some of your spunk on your belly. Her face has a look of pure lust, not in keeping with her previous feigned innocence.
What now?
