I have 4 children of my own and 3 nieces/nephews already, youngest of all, bar this little one is 5. My new nephew is 3 months old and I can't help worrying about him. He's not yet smiling or doing anything in fact, he does hear and see but is very expressionless, tongue forever hanging out(making him look vaguely gormless!!) What's going on, why no smiles, giggles or anything? Please reasure with loads of plausable explanations.