Puberty Timing: Why Do Girls Start Earlier Than Boys?

Girls typically go through puberty before boys, with the average age of onset being 10-11 years for girls and 12-13 years for boys. There are a few reasons for this difference:

1. Genetics: The timing of puberty is largely determined by genes, and some genetic variants are more common in girls than in boys.

2. Hormones: The hormones oestrogen and progesterone, which are produced in greater amounts in girls than in boys, play a key role in triggering the onset of puberty.

3. Body fat: Body fat is necessary for the production of oestrogen, so girls who have a higher percentage of body fat tend to start puberty earlier.

4. Environmental factors: Certain environmental factors, such as stress and poor nutrition, can also affect the timing of puberty.

However, it's important to note that there is a wide range of normal ages for puberty to begin, and some boys may start puberty before some girls.