Is it normal that a person has deeply interest in any scientific matter since childhood?

I hope so. I (osteopathic medical student dave miller) first got interested in biology when i was about 6. Now my son is 6 and he's nuts about paleontology. Nothing wrong at all with an early, sustained interest in science.
It's GREAT!!! In fact, much of what's wrong with our world is reflected by how many more children are told to care more about paris hilton and justin bieber than about learning how the world is put together and the secrets of the universe, the human body, and the human mind. Kids naturally want to learn, and the more focused they are on science, the more useful they will be career-wise later on.