I can't ever remember not wanting a dog. My entire childhood was spent reading about dogs, looking at pictures of dogs, pretending to train my stuffed dogs, and chasing down passers-by begging to pet their dogs.
I walked all the dogs in my neighborhood. I attempted to catch every loose dog I saw. I desperately wanted a dog of my own, and I was always hoping that maybe wouldn't be able to find the owners and I would get to keep one of those strays, just like in my dog books. Of course, we always managed to find their owners, and my parents really didn't want to deal with a dog so they always had an excuse why I couldn't have one. Our yard wasn't secure enough, dogs were too expensive. They said wouldn't want to feed it or walk it or clean up its poop. Every breed was either too big, too small and yappy, too noisy, or potentially aggressive.
I don't think they ever understood how much it hurt for me to not have a dog. Real, actual pain. It was a constant, aching void. Nearly every day I would find a place and time to quietly cry that I didn't have a dog. I had an imaginary dog that followed me everywhere, something I could pretend was taking up that empty spot behind me where my dog should be. I could never make anyone understand how utterly incomplete I felt, without something that I had never had.
Dogs have been following human beings around for 30,000 years, that's longer than we've had agriculture or permanent settlements. It's longer than we've had writing, and almost as long as we've had language. Maybe it's long enough for people to have evolved adaptations around dogs. Maybe dogs became ubiquitous in human culture because some of us actually need dogs. I really don't have any evidence to back up this vague idea, it's also distinctly possible that I have some sort of mental disease involving dogs. At any rate, when I was 12 one of the dogs I walked regularly was offered to me because her family was moving, and my parents finally, finally let me have a dog.
It has been nearly two decades now, and the novelty still hasn't worn off. It might have actually gotten stronger. I am heavily involved in dog rescue, have competed in dog sports, and advocate for animal welfare and humane legislation. Training my dogs is one of my primary hobbies. I currently work at a dog daycare, and started a dog blog about Awesomedog, Tinydog, and my various foster dogs. Having dogs has been every bit as awesome as I always imagined, if not better.