Remember, these effects do vary. Not everyone is the same!
Because of your KS/XXY you will probably taller than the rest of your family.
Your legs and arms may be slightly longer too.
You won’t develop as much muscle as some of your mates. Working out with weights will increase your strength.
You may not develop much hair under your arms and you may not have to shave very often. However, you will be less likely to go bald - until you start taking testosterone.
Your genitals may be smaller than some of your peers.
You might be inclined to put on weight easily round your stomach and hips - or you may be quite skinny.
Keeping active will help to keep your weight down.
Your muscles might stretch easily. This is called hypotonia. It can cause flat feet and it can make you a little clumsy.
Sometimes during puberty, boys develop breasts.
This is called gynaecomastia.
Usually this disappears but, with KS/XXY young people, sometimes it doesn’t.
Some young people don’t mind but, if it upsets you, ask your endocrinologist or GP for help.
They might recommend an operation to remove the excess tissue.
All the people in this photo have KS/XXY. Many of them are tall, but not all. Some are overweight, but not all.