Medical experts state that the average age for the onset of puberty has been decreasing globally over the past three decades, influenced by factors like nutrition and environmental changes. For girls, puberty typically begins between ages 9 and 13, making an 11-year-old start within the normal range, often marked by breast development. In boys, puberty usually starts between 10 and 14 years, so 11 is also considered typical. However, doctors emphasize that a child's overall developmental stage and maturity are more crucial indicators than age alone.