To tell you the truth, considering the age of the brother and sister, it is quite normal that the brother became aroused by the sight of the naked girl in front of him. Maybe what happened next is not part of the plans of normality, but tell me honestly, would you resist such a dark-haired beauty? That's what I mean.
Every daughter has to learn how to have sex. And it's good when parents are understanding about it. Her father tried to teach her the easy way, but her mother said she knew better how to suck and wiggle. They decided not to touch her ass yet, but they taught her good manners in the pussy and the mouth. The mother turned out to be a skilful master and taught her daughter the right technique. What a wonderful family!
Now I know what I'm gonna do when I meet my brother (I'm gonna suck his dick).