Full Set of Teeth at Birth - Possible?

I have a dual GQ this morning. My useless knowledge gadget on iGoogle displayed the following tidbit today:

This gadget is not the most reliable source of “facts”. It has presented some that I know to be disproven. This one in particular intrigued me. The 2 questions are:

  1. Is it possible for a child to be born with a “completely developed” set of teeth?
  2. Was Betsy born ready to gnaw an ear of corn? If so, I bet her mom hated feeding time.

It’s possible for milk teeth to be up and ready at birth…

It would be freakishly unusual for adult teeth to have grown in at birth - and if such cases exist, the result must be serious overcrowding, or else very small, spaced-out adult teeth later in life

My question is, how would anyone today know this about Betsy Ross? The stuff we know about even famous people of that era is sometimes rather sketchy. Why would the state of Betsy’s teeth at birth have been preserved down the generations?

It reminds me of something you might have heard on Paul Harvey’s “The Rest of the Story”.