Since your kids could talk, you've answered, oh, a zillion questions about everything from how come the dog's legs twitch when he sleeps to why grandma puts that green stuff in the spaghetti sauce, but boy, the questions that come with the onset of puberty are tough. (On the other hand, life with zero questions about puberty isn't desirable either.) Sure, we've all been through puberty and lived to tell the tale, but the topic does tend to make kids and parents alike a bit squirmy. Here are the facts you need to know, plus tips on how to have the conversations (yes, plural) you need to have without either of you bursting into flames of embarrassment.

Puberty refers to the time period when a child is physically developing into an adult. For girls, puberty generally occurs between ages 9 and 13; for boys, it's ages 10 to 15. We've all heard that puberty is occurring earlier than it did in previous generations, especially for girls, but is it true? Dr Jean Emans, chief of the division of adolescent medicine at Children's Hospital Boston and professor of pediatrics at Harvard University, says that menstrual periods start an average of only four months earlier than three decades ago, which is probably related to increased body weight and nutrition. On the other hand, Lynda Madaras, a puberty educator and author of the popular "What's Happening to My Body?" series of books, says that more and more girls are showing the first signs of puberty in grade three or four or even earlier. Whatever the age, puberty is a time of complex physical and emotional changes. And if you're concerned that it's happening too early or late, talk to your doctor.