Where did the past 4 months go?

And how did this kid get so big? We just took him in for his four month well check, he weighs 17 pounds and 11 ounce. He's only 3 pound less them Alina. We get asked all the time if they are twins. He's huge and she's bald, so side by side they look the same age. Until she start loving/pounding on him, and you notice that he has to sit there defenseless, without control of his body. That heavens he loves her. He loves all the kids. He's big eyes just follow this kids around all day. He is a perfect little angel.