Thanks for the information.
@Mae Bell Perry, that is possible. One example, often it is a result of the biological mother dying and a step-mother joins the household but her relationship status is improperly marked. But there are many other causes some correct some because of some type of data error etc. You really need to give more detail or better yet post the PID of the father if you want a more exact answer.
Oops, I was answering as if you had posted in the Family Tree Category
Please provide your batch code. The batch code is located at the top of your indexing screen and looks like [1111-AAA] and is also located under Batch ---> About Batch. This allows us to get a better look at the problem.