Most folks remember puberty – and not always in a good way. It can be an awkward stage of budding breasts, unwanted hair, acne and unexpected body odor. Puberty, when a child undergoes physical changes and becomes sexually mature, typically begins around age 8 in girls and age 9 in boys.

But imagine, say, a 6- or 7-year-old undergoing such changes? Studies are showing that the onset of puberty for both boys and girls is occurring earlier and earlier, a phenomenon defined as precocious puberty.

A study published in Pediatrics in 2010 found that among a population of 1,200 American girls, about 23 percent of African-Americans,15 percent of Latinas and 10 percent of Caucasian girls had begun puberty (marked by breast development) at age 7.

In 2012, another study published in Pediatrics found that puberty in American boys – measured by testicular enlargement and pubic hair growth – was beginning six months to two years earlier than what research in previous decades had documented, particularly among African-American children.

There are two types of of precocious puberty, explains Dr. A. Pinar Cemeroglu, a pediatric endocrinologist at Helen DeVos Children’s Hospital in Grand Rapids, Michigan. True or central precocious puberty happens when the hypothalamus, the brain region that manages hormone production, sends signals to the pituitary gland. The pituitary gland, in turn, tells the ovaries in girls and the testicles in boys to produce estrogen and testosterone.

Usually there is no known medical reason for central precocious puberty, though in rare cases, the cause may be a condition such as hypothyroidism, a tumor or injury to the brain or spinal cord.

False (pseudo) or peripheral precocious puberty occurs when hormones are produced from the ovaries in girls, testicles in boys or adrenal glands in both boys and girls without the involvement of the hypothalamus and pituitary gland. This could be due to a genetic condition or tumor, Cemeroglu says.

In addition to the bodily changes typically associated with puberty, “precocious puberty usually causes the bones to fuse early, ultimately causing short stature,” says Dr. Carlo Reyes, a pediatrician and assistant medical director of the emergency department at Los Robles Hospital in Thousand Oaks, California.

“Though [these children] usually appear to be tall for their age at the time,” Cemeroglu explains, “[they] stop growing earlier than their peers and end up being short adults or shorter than what their genetic potential dictated.”

While the physical effects of precocious puberty are obvious, the unseen social and psychological ones can have just as great an impact. Experts note that early puberty is associated with anxiety, depression, eating disorders, early sexual activity and substance abuse.

“The emotional risks are daily,” says Dr. Danelle Fisher, vice chair of pediatrics at Providence Saint John’s Health Center in Santa Monica, California, “from the interaction with peers who are not at the same hormonal, emotional and physical levels to the loss of a sense of childhood when the body matures too quickly.”

As for why a growing number of children, especially girls, are experiencing early puberty, there may a number of culprits. For some children, it could just be hereditary, Cemeroglu notes. “Knowing when puberty began for a mom or dad or sibling can be helpful in predicting possible genetic factors causing puberty onset,” Fisher says.

One possible reason for the rise in precocious puberty could be the obesity epidemic in America. According to the Centers for Disease Control and Prevention, in the last 30 years, childhood obesity has more than doubled in children and quadrupled in adolescents.

In a seven-year study tracking more than 1,200 girls – published in Pediatrics in 2013 – researchers noticed that those with a higher body mass index experienced earlier puberty as measured by breast development than those with lower BMIs. Body fat, it should be noted, releases estrogen, which contributes to breast development.

Diet may also play a part. A study published online last January in Human Reproduction found that among a group of nearly 5,600 girls ages 9 to 14, those who drank more than 1.5 servings of sugary drinks such as soda, sweetened fruit drinks and sweet tea a day had their first period nearly three months earlier than those who drank two or fewer sugary drinks a week. This was independent of the girls’ BMI, how much food they ate or whether they exercised. And while the researchers clarify that it’s unclear why the consumption of sugary drinks may instigate early menstruation, it is safe to say there’s an association.

There is also evidence that emotional stress may impact when a girl begins puberty. A 2007 study published in Child Development found that girls who grew up in homes with poor parental support, martial conflict and with depressed fathers experienced their first hormonal changes earlier than other children.

Findings such as this have led some experts to theorize that precocious puberty may be an evolutionary response to one’s environment – the body’s way of ensuring the survival of genes under stressful and possibly dangerous conditions by becoming sexually mature earlier.

How to treat early onset puberty depends on the underlying reason. In central or true precocious puberty, a child may be given a medication that delays further sexual development either via monthly injections or a small, under-skin implant that gradually releases the medicine. “If precocious puberty is peripheral, then the cause is usually a sex gland overproducing hormone, for which surgery may be needed,” Reyes says.