By Allison Salerno The creature emerging from our nearly 12-year-old younger son is something we already are raising: a teenager. Living as a peri-menopausal woman with two instead of one moody boy in a family, however, is different than coping with one. Already this morning they were bickering before breakfast over who had to walk the dog. Later, a hungry 14-year-old walked by and grabbed waffles off the breakfast plate of the 11-year-old, who is hungry All. The. Time. ("Mom, you've been telling me for years I am about to have a growth spurt"). And it wasn't even 9 a.m. As any parent knows, every child is different. The teen years of our first, a reflective, artistic soul, are going to be much different, I imagine, than that of our family's lone extrovert, who always has had a posse of pals and "met" the principal on his first day of middle school. (The details are dim but something about storming the cafeteria doors when the students