Teenage Problems 1 Hormonal changes lead to physical and sexual maturity throughout puberty. It might be challenging to predict when guys will reach puberty. There are changes that take place, but they do so gradually and through time rather than all at once. Although every male teenager is unique, the following are typical ages at which puberty changes may occur: Age range for the onset of puberty: 9.5 to 14 First pubertal change: testicular enlargement Penis enlargement: starts about a year af