
You arrive at this conclusion because your classmate "and his sister are both much shorter than their parents."
Explanation:
As we start getting older, the bones begin to become thinner. Respectively of the vertebrae converts to become a little shorter. Therefore, so do we. With full-blown osteoporosis, people can lose several inches in height. The average height of a woman in the U.S. is about 5 feet, 4 inches, up about an inch in the last few decades, according to the Centers for Disease Control and Prevention. The study adds to growing interest in early-life events that influence adulthood.