well you can never rule out ones imagination. they may be very trustworthy, sometimes people want a laugh [but i'd like to believe this isn't the case] you should still try and rule out anything logical.
if you feel there is a spirit or something, there are ways to communicate, meditation can put you in a state where it's easier to hear spirits. [they might not always talk though, there's been many times spirits in my home would pace the room waiting for me to stop meditating] keep a journal nearby to record anything. you can also try a pendulum, skrying, or other divination tools. if you feel they're friendly, you can leave them alone, you could also simply ask them to leave. if you feel uncomfortable or your family seems scared, you can always cleanse the place and cast a protection on your, your family, and home.