20-30 inches is normal i have a 14 month old and just came from the doctor and she said that's normal height.
it usually varies- but the height of a baby when it is one year old, times 3 is the height it will be when its an adult... TRUE fact!!!
the baby should be about two foot 6
don't know depends how healthy they are
Well i'm no way near 19 but i'm around 5ft. I've met a 19 year old who's 166cm which is in between 5ft and 6ft. i think the average should be about 160-180 or so :3