No, don't say "family reasons." I'm afraid that even at smaller schools or those in less popular locations, there is too much chance that this will translate into "my job is not a priority"--especially if you are female.
Instead, use any insight that your family connection to the area provides you to praise something else about the school or the immediate area. If you love hiking, if you're fascinated by the city's new plans for X project, if you can't wait to resume Y childhood hobby--say that (in addition, of course, to emphasizing the specific department and institution) rather than "family reasons."
And, yes, it makes me very sad to give this advice.