Height is related to age, but even more closely related to bone age. Age, also known as the natural year, means that in the natural year, a child may develop only 0.5 biological years, called the bone age year, or 1.5 biological years, or 1.5 years of bone age. A child’s lifetime growth bone age has been limited, so if he or she grows 1.5 bone years in a year, he or she may be taller and may not actually end up as tall as a child who grows 1 bone year in 1 year. The final height is not judged by age, but by bone age. Therefore, even if a child is the tallest in the class, it does not necessarily mean that he or she will be the tallest in adulthood. Therefore, we still need to check the bone age to determine the final height. Some children may be short, but their skeletal age is also below their age and they have more potential to grow taller in the future. Not everyone is a late developer, and late development is not a direction to be considered routinely. Whenever possible, follow Japanese logic and have a bone age screening every 2 years to make an assessment of your child’s future height development.