What we think we know about giraffe height is a tricky thing. At the San Diego Safari Park I have heard several tour guides say "The Baringo giraffe [what they call Rothschild's] is the tallest giraffe subspecies". I have asked several zoo people and all of the giraffe researchers that I know where this "fact" came from and nobody knows. I don't think that anybody knows what the tallest giraffe species is.
Regarding baby giraffe height, as with the size and weight of human babies there is variation in giraffes, so very likely there are some baby giraffes taller than six feet and some baby giraffes smaller. Possibly most baby giraffes follow the rules and come out at six feet (although I'm not sure how good the data is on this).
