What are the physical symptom of the disease?

As babies, many of the males have weak muscles and not much strength. The may sit up, crawl, and walk later than other babies. At about age 4, the males tend to be taller and have a lack of coordination. When they enter puberty, beacause they have a small amount of testosterone, they might have a taller, less muscular body, and less facial and body hair, and broader hips than other boys. As teens, the males may gave larger breasts, weaker bones, and a low energy level than other boys. At adulthood, they look like males without the condition, though a bit taller. Though they are more likely than other males to get certain health problems, such as autimmune disorders, breast cancer and etc. Also 95 to 99 percent of the males with klinefelters are sterile, which means they can't have children.

http://www.andrologyaustralia.org/images/pageContentImages/KlinefeltersIMG.jpg