Correct. Balto is NOT the offspring of Togo. While it could be hypothetically possible, it is extremely unlikely, and the pedigree of Togo doesn't support that claim. I say this because, the year of the Great Serum Run, Togo was twelve, and Balto was only three. There was, as you see, a substantial difference in age between the two dogs.
Whomever claims that, however, has no idea what they're talking about (and I don't care if they know I said that either). This kind of stuff happens when people (whether teenagers or adults) start yammering off about a subject without doing RESEARCH, and respecting HISTORY. They make all manner of bold, unsubstantiated claims, and pass them off as FACT (and ardently defend their beliefs that their assertions are correct). If they only took a little time to do a little easy research (and in this day and age, it isn't rocket science), then absurd claims like that would vanish. However...since people are generally stupid and lazy...and love to spin yarns...
The fact is that the real Balto's pedigree has yet to be uncovered. That would solve the mystery of who his parents are. Togo's pedigree, however, makes no mention of Balto:
PEDIGREE (read from right to left):
http://aussie.mercurialmedia.com/pedigree/pedigree.asp?ID=AWSH229
DETAILS*:
http://aussie.mercurialmedia.com/pedigree/dynprofile.asp?ID=AWSH229
SIBLINGS:
http://aussie.mercurialmedia.com/pedigree/siblings.asp?ID=AWSH229
OFFSPRING:
http://aussie.mercurialmedia.com/pedigree/progeny.asp?ID=AWSH229
*The one error here is that Togo is listed as having had BROWN eyes. However, most of Seppala's line of dogs had blue eyes (with some exceptions). Take a look at these two close-up photos of Togo as evidence of the fact that he did, indeed, have ICE BLUE eyes:

