Not all males with the condition have the same severity when it comes to symptoms. Symptoms vary because the patient may have a different amount of XXY chromosomes as another. The age at which the patient was diagnosed also matters.
The XXY condition can affect three main areas of development:
Physical development: As babies, many XXY males have weak muscles and reduced strength. They may sit up, crawl, and walk later than other infants. After about age four, XXY males tend to be taller and may have less muscle control and coordination than other boys their age.
As XXY males enter puberty, they often don’t make as much testosterone as other boys. This can lead to a taller, less muscular body, less facial and body hair, and broader hips than other boys. As teens, XXY males may have larger breasts, weaker bones, and a lower energy level than other boys.
By adulthood, XXY males look similar to males without the condition, although they are often taller. They are also more likely than other men to have certain health problems, such as autoimmune disorders, breast cancer, vein diseases, osteoporosis, and tooth decay. XXY males can have normal sex lives, but they usually make little or no sperm. Between 95 percent and 99 percent of XXY males are infertile because their bodies don’t make a lot of sperm.
Language development: As boys, between 25 percent and 85 percent of XXY males have some kind of language problem, such as learning to talk late, trouble using language to express thoughts and needs, problems reading, and trouble processing what they hear.
As adults, XXY males may have a harder time doing work that involves reading and writing, but most hold jobs and have successful careers.
Social development: As babies, XXY males tend to be quiet and undemanding. As they get older, they are usually quieter, less self-confident, less active, and more helpful and obedient than other boys.
As teens, XXY males tend to be quiet and shy. They may struggle in school and sports, meaning they may have more trouble “fitting in” with other kids.
However, as adults, XXY males live lives similar to men without the condition; they have friends, families, and normal social relationships. 
