So you are saying the clerk guessed at the age on her own? How about the mother or grandmother guessing at the age or just repeating what they thought was the truth? You have a problem considering possibilities that don't support the conclusions that you've already reached.
BS, no it's not!
Look at an image of the actual document. "Gretchen" is closer to the line than "Carter Nordyke."
You can see something similar with the parents' names and races: "Robert" looks higher than "Nordyke." "Eleanor" is further from the line than "Caucasian." If you want to take out your microscope and count pixels go ahead. That may have something to do with being bound in a book, but it happened a lot in old forms that the names didn't line up as exactly as they do on today's computer forms.
And I notice the numeric digits are somewhat larger than the alpha, even larger than the capitalized letters, and this makes the bottoms lower than the alpha text on the same lines. And the words are centered in the fields (sometimes) and do not line up perfectly (very similar to the Obama document). And some of the letters are not perfectly formed and some are lighter than the others.
This document must be a forgery.