Hi...., height is entirely genetically determined... Men grow height-wise until 21 years old, although depending on the person they may experience slight changes until 25. It is really difficult to increase height after the age of 25, primarily due to the fact that the bones stop growing at this age ... about 20% or more of our body height depends upon external factors like your environment, activities and diet. If you follow certain basic things in your daily lives, you can increase your height in a natural way....