A 6'6" person saying they were
something other than tall as a kid is like a
black guy saying he was white until he turned 18. What else could you have been even if
you tried?
People would know a 6'6" person was always tall for their age as a kid without them having to explain it,
the same way they would know a 4'10" person was always short for their age, even as a kid (unless they are
one of those rare Guinness record books folks), so
explaining it would be redundant.