It should be known that Andrew and Andrea don't just have sex for fun nor do they do it to make a baby. It's their way of showing each other just how much they love one another.
Andrew is engaged to Summer Beeko (hairy were-Gazelle) and Andrea is dating, Summer's baby brother, Fitshaced. The Beekos engage in incest too for pretty much the same reasons that Andrew and Andrea engage in but he Beekos are proud to admit that they love their fellow family members.
Of course, maybe one of the reasons why the O'Connells don't admit their ancestral relationship is because they are afraid of what people would think. Then again, just the thought of doing something so wrong in secrecy is stimulating.
first i thought it was some kind of werewolf or other normal furry.... then when i took a closer look... i died a little inside... ;______; why.....! ;A;