I would tend to agree with users such as cliverederson, pftsusan, and intothebleach. My dogs are definitely my children. I don't even want children in real life, but the maternal feelings I have towards my two dogs is unreal. I've always had more understanding and love for animals than I do for human children, as strange as that may seem. I don't really like cats, and am definitely a dog lover, but I understand that people feel equally strong about including them as members of the family. I would do anything for my dogs just as a mother would for her children. That being said, to me, pets are definitely family.
I don't think this bond is exclusive to dogs and cats either. On another post I was just talking about Kevin Richardson, "The Lion Whisperer," and the amazing bonds he has with his hand-raised lions. Other times there have been elephants that had extremely deep bonds and attachments to their handlers in captivity. I do believe that some mammals tend to form these types of familial bonds over other species such as reptiles and birds, but that does not mean that pet owners do not care just as deeply about their pets to consider them as family.