It depends on which country's army!
You should contact a local army recruiter and consult it with them.
https://perscomnd04.army.mil/langsurv.nsf/langsurvcentopen
You can sometimes get a medical waiver from the Army if you have been on antidepressants. The standard is that there is a three years waiting period before you can be considered for a possible waiver. There are no guarantees.
U.S army
Situation dependent. It might require a waiver, and now isn't the hottest time to reenlist under a waiver.
Yes, klinefelters is waiverable in the us army but the marines or navy will disqualify you if they find out.
You must speak to a U.S. Army recruiter about obtaining a waiver. Your background will have the most bearing on the considerations that can be made. Each case is considered individually.
You would have to speak to a recruiter to determine if you were eligible to enlist on a waiver.
Typically, the answer would be no. However, it may be possible to receive an entrance waiver. Your local US Army recruiter could advise you better on this.
You must be 18 to join the Army, but you can get a waiver if you are 17 and meet certain requirements. Contact a local recruiter.
train forcombat proficiency
a soldier who is a member of a legion (especially the French Foreign Legion)