Natalie, the biter

Since the moment Natalie was born, older sister Lauren hasn't liked her too much. Almost from the beginning Lauren was mean to Natalie--hitting her, pinching her, trying to pull her off me or pull her off the couch or bed when she was sleeping... the list goes on. Well, the time has come when Natalie is fighting back. And she has learned from the best. Today Natalie and Lauren were laying on the ground, watching Dora and suddenly I hear an ear piercing scream!!! Natalie bit Lauren's leg for no apparent reason. Lauren now has an awful mouth sized bruise on her leg. These two are 2 years apart and have definite sibling rivalry issues. They fight over me all the time. I have plenty of room on my lap, but next thing you know they are pushing, pulling hair, pinching, biting, fighting for my whole lap to themselves, until, I eventually can't take it anymore and get up, leaving them both crying on the couch. I can only hope that this won't go on forever.