A study conducted in the United States of America has zeroed in on the culprit behind the falling age of attaining puberty. A gene has been isolated which is said to be the cause for girls attaining puberty as early as 8- 10 years. However the most widely held explanation for this is growing childhood obesity, intake of rich foods and lack of physical activity.
Also scientists were keen on the role of estrogen, a female hormone, in attaining puberty.
They were surprised to learn after their investigations, that the breakdown of testosterone, the male hormone, in the body and also the effects of a gene, which induces the onset of puberty, determine the age of puberty. 
During the age of puberty, girls develop breasts and other secondary sexual characters.
The gene called CYP1B1, acts by breaking down testosterone in the body of these girls and this starts off a cascade of hormones, which result in breast development.
The scientists are now studying the effects of this gene on puberty in boys. Using the same yardstick they reason out that those with CYP1B1 gene should attain puberty later than other boys because the gene breaks down testosterone, and this, male hormone is essential for attaining puberty. 

