The short answer is yes; it is wrong. We can see the importance of this in a story concerning Noah. God had already preserved him and his family by the flood. Noah wrongfully became drunk and, not knowing what he was doing, become uncovered in his tent. The story continues:
Genesis 9:22-24 And Ham, the father of Canaan, saw the nakedness of his father, and told his two brethren without. And Shem and Japheth took a garment, and laid it upon both their shoulders, and went backward, and covered the nakedness of their father; and their faces were backward, and they saw not their father's nakedness. And Noah awoke from his wine, and knew what his younger son had done unto him.
The family of Ham received a curse because he went in, looked on his father's nakedness, and went and told about it to his brothers. Notice how carefully the other two sons (Shem and Japheth) are to cover their father without looking on him. There are other places where this is taught in scripture, but this passage should settle the issue. We are not to look on the nakedness of family members.
Now, I realize that there are some exceptions to the rule. God says that a husband and wife are one flesh (Genesis 2:24) and that the bed in marriage is undefiled (Hebrews 13:4). There is certainly no such restriction between a husband and wife. Another exception would be in dealing with small children. They must be cleaned and cared for. And, while they are very young, they are totally innocent in their understanding. A third exception must be made for illness. Sometimes, people honorably care for aging parents or for other family members in time of grave illness. Yet, though the body might be seen, there are certainly ways to maintain modesty as much as possible. And, certainly, accidentally glimpses of family members is not a sin. Just turn away, keep going, and try to avoid situations where this might happen.
However, this gives no excuse for older children or adult family members to look on the nakedness of others in their family. Another verse to consider is Leviticus 18:6 - "None of you shall approach to any that is near of kin to him, to uncover their nakedness: I am the LORD."