Over the course of several years, a man's body will undergo several rapid changes as he progresses toward sexual maturity. At the end of this process, a man's physical growth will end and he will be able to father children because his reproductive organs have developed fully. The process of sexual maturity can begin and end at different times, and some men reach sexual maturity several years before or after their peers. A young man and his parents can see many of the changes which indicate that puberty is occurring.

Reaching Sexual Maturity

For most boys, puberty begins somewhere between 9 and 15 years old, according to the TeensHealth article, "Everything You Wanted to Know About Puberty." During this time, a man may gain at least four inches per year in height; he also develops broader shoulders and a deeper voice. His facial and body hair grows and a boy may notice an increase in body odor. He may develop acne, and his genitals become bigger. Sexual responses also become more common, with men experiencing more frequent erections and are able to produce semen at ejaculation. Emotionally, this process usually ends with sexual maturity ranging from age 12 to 18, according to Dr. Marie Hartwell-Walker in the "Psych Central" article, "When Does Sexual Maturity Arrive?" If you are between these ages and you are not sure if you have started puberty, speak with your doctor.