The closure (complete change from cartilage to bone) of the epiphyseal plates in the long bones is the end of any chance of height increase. This can occur any time between the age of 15 up to age 20 or so (on average). It is genetic and based on the ratio of male to female hormones, the timing of puberty and which genes are inherited from both parents. It can't be predicted accurately and it IS possible to resume more rapid growth after a prolonged period of slow growth because other health issues, medications, etc. can stall that growth for a time.

Devon Smith