I get the impression that you may have experienced some family intimacy from your comment. My wife could tell you many stories of passionate intercourse with a sibling and an uncle who kept her vagina wet with family love seed when she was a teenager. She claims that the sex was so enjoyable that she couldn't resist lying back fully naked as they filled her vagina with semen. She didn't have sex with them at the same time because both of them wanted a private and protracted love session to enjoy her lovely sexy body before they reached a climax in her pussy.
What a fantastic family fuck session. The boy gets to fuck his sister and his mom and the old dad fucks the mom and the girl too. I know that this is all staged but the concept is great and it attempts to illustrate what really happens in a family that keeps sex "in the home". If you really think about it, sex is a natural act of pleasure and the best person to share it with is an affectionate family member. The only thing that makes it taboo is the fact that a fertilization could occur and that would not be a good thing. Otherwise, I say that any family who agrees to engage in sexual intimacy should persue it with vigor and enjoy the generous exchange of family love juice. .