There may be a reason for this. Your dog may think HE is the leader of the pack!
Dogs are instinctively pack animals. In a pack, there's a pecking order to the group, with the alpha dog being at the top. The alpha is the strongest of the pack; he sets all of the rules and maintains the order of the pack.
When you introduce a dog to your family, to him - it becomes his new pack. Whether you know it or not, he will be feeling out his role is the hierarchy. If he is a dominant dog, you might find yourself in stiff competition to establish who is alpha.
The pecking order is like a ladder, where the alpha is at the top, followed by a second in command and so on. If you're at the bottom, then you're not in charge of anybody, and your dog will seize the opportunity to be in control of the situation.
You don't want your dog to think he's above anybody in the family. So it would be a good idea to make sure your entire family understands this concept and follows it.
Here are some steps you can take to establish yourself as the leader of your pack:
Dog Training Secrets.

Don't let your dog sleep with you! We all want our dogs to sleep with us, but if he sleeps with you, he'll consider himself apart of the litter and equal or above you. The alpha dog always sleeps alone, in the most comfortable spot.
Walk through doorways first before your dog. The alpha always enters the den first, and has control over the room. So tell your dog who runs the show when entering a room, especially the front door.
Always feed your dog after you eat. Make sure the whole table is clean and some time has passed, then it's OK to feed him. If you feed him about two hours before you eat, this should be all right as well.
The alpha dog is never indecisive; he makes decisions and sticks to them. If you reprimand your dog or give him a command, make sure you follow through with it.
If he is completely disobeying and being unruly, gently place him on his back, hold him firmly and look him in the eyes. Keep him there until he relaxes. This means he's submitted to you physically. Dogs fight, and when you do this you show him who's the boss and who calls the shots.
Under no circumstances should any of these methods ever be too rough or harsh. You don't want your dog to fear you; you want him to respect you.
There is never a reason to mistreat your dog to show him you're in control. Choose a dog training guide that teaches a method you're comfortable with and expand on these ideas