Kallmann's Syndrome is not a very well known condition, even in the medical community.

The actual incidence is difficult to know for certain but estimates are in the range of 1 in 10,000 for men and 1 in 50,000 for women.

On one hand it is a very mild condition to have, there is no change in life expectancy and no pain associated with having the condition. The only big thing to watch out for is the increased risk of developing osteoporosis, or "brittle bones" due to the low levels of circulating sex hormones. The lack of sense of smell may get noticed from time to time and may cause a few embarrassing or awkward situations during life.

However the psychological damage of not going through puberty at the same time as you peer group, or even not all, can be immense. Just how damaging will depend from individual to individual and will be affected by age of diagnosis / treatment, knowledge of the condition and family & friends.

There are two aspects of not going through puberty that have to be considered. One is the feeling of being physically different from the people around you and the other is the fact that you will be infertile without treatment. Each of these may be more important than the other depending if you are male or female or at what stage of life you are at.