True or False? By age six, children’s bodies are proportionately not very different from those of adults.

True – to some extent.
Yes this is true – to some extent. By age six, your “chip off the old block” is indeed on the way to becoming a mini-block himself or herself. But six year olds are not miniature adults.
As people grow, body proportions change. For instance, at birth, the head accounts for one-quarter of total body length. In adulthood, the head typically counts for one-seventh of height.
And other parts of the body grow at different rates too – which leads to gradual changes in ratios of one body part to another. Let’s look at the crown-to-pubis distance compared to the pubis-to-heel distance. Simply put, that’s a comparison of the upper section of the body to the lower section. At birth, this ratio is typically 1.7. Then, as legs lengthen in relation to the rest of the body, that number goes down to 1.5 at one year old and 1.2 at five years old. By age seven, the ratio is 1.0, indicating that the upper and lower parts of the body are of equal length.
See your child’s physician if you have any questions about this aspect of growth measurement.