Sheesh, just because some folks have such perverted minds doesn't mean everyone does.
1. Nude does NOT equal sexual.
2. Sitting next to each other even if they were nude does not mean they were doing anything.
There is nothing wrong with nudity. Too many people can not grasp the concept that it is possible to see someone who happens to be nude and not have sexual thoughts. Many people see nudity as no different than seeing a person clothed, in fact some clothing that people wear are much more sexualized than nudity itself.
Consider that historically nudity was never so much of an issue for most folks up until this past century. In the past families were much larger and homes much smaller. That meant that kids often shared bedrooms and even beds, and this even included cross gender. Yes brothers and sisters slept in the same bed growing up. They also didn't have the nice porcelain bathtubs so many are used to today, instead they took baths in the creek or in a big metal tub. This tub was set up either in the yard or in the kitchen (close to the fire where you heated up the water and you didn't want to carry it too far). These baths were done in front of everyone one else in the family and sometimes even neighbors. No one thought the worse of it as that was just the way life was.
Even further back in history clothing was difficult to make and expensive. Thus most folks only owned one or two sets of clothing at best. With that they would do their best not to wear them out too quickly and so you often saw folks working in the nude, such as farmers and fishermen. Kids would often play nude for the same reason and slaves were generally nude as you didn't want to waste money clothing your slave.
So not it's not bad, there is nothing wrong with being naked and even if you are sitting no the same bed or couch together. Go visit a naturist resort and see just how non-sexual nudity really is.