My ex-father-in-law walked into our bedroom when we rented a cabin at Lake Tahoe. Late at night he had just won a big jackpot and need to get into the driveway, but my car needed to get moved. He figured we were asleep, so he quietly opened up our door to get the keys to the car. We were full on fucking on the floor, only had two twin beds. He said that he was sorry, but needed the keys, I said they are on the nightstand and I'll get them. He said, no, stay there, I'll get them and stepped over us. He then had to step back over us to leave. I bet he was shocked to see his son getting plowed. He left the keys in the kitchen.
Now my Mom lives with us and she's always here, so yes, I do have sex with other family memebers in the House.