For obvious reasons, it is important that information that is entered be as accurate to the best of your knowledge. If it is not important to maintaining the geneology, then it need not be entered.
For example. I have never had a stepmother, yet one is listed on my family tree. My father has a domestic partner that he met after his children were grown and had children of their own. While their relationship may be important, it has no bearing on the family tree. This is not meant to be insulting, it is just to remind people these are facts, not a touchy feely site.