DEAR ABBY: I’m a mother of three beautiful little girls. I’m nervous about having to talk with my oldest about puberty and sex. She’s turning 10, and I know I need to start explaining certain things to her, but I have no idea how. My mother never sat me down and talked to me about anything, really, so my mom would not be of much help. Any advice you can offer would be greatly appreciated. MINNESOTA MOM OF THREE DEAR MOM: You can spare your daughter a frightening experience when her first period arrives if you start talking to her now, before ...