Short answers, pulled from the story.
The brain's hypothalamus releases pulses of gonadotropin-releasing hormone to initiate puberty. These signals travel to the pituitary gland which secretes luteinizing hormone and follicle-stimulating hormone into the blood.
Females typically begin the process of puberty around age ten and a half while males start at ages eleven and a half to twelve. Puberty generally ends between fifteen and seventeen for females and sixteen to seventeen for males.
The average age at which the onset of puberty occurs has dropped significantly since the 1840s when it was age 15 for females and 17 for males. A 2006 study in Denmark found that breast development started at an average age of nine years and ten months.
Early-maturing females usually look larger than females who have not yet entered puberty and may face teasing about their visible breasts. These experiences lead to lower self-esteem, more depression, and poorer body image among affected individuals.
The Centers for Disease Control and Prevention found measurable amounts of BPA in the bodies of more than 90 percent of the U.S. population studied. Many plastic baby bottles contain BPA and it is more likely to leach out when temperature is increased.