Because she is his sister, he can only fuck her ass
Lying on the floor of the living room where they used to play, she is naked right there. Her legs are spread and she can’t wait to start feeling the tickles she always feels. And he doesn’t have to do it because his brother comes right there to lick him. Or what is known as oral sex, which according to the laws and the Bible, does not count as incest. Therefore, after she is well aroused, he penetrates her. He can only fuck her ass since she is his sister and they don’t want to commit any sin. They are very religious and you can see that in the way he is fucking her.