The point is that you shouldn't always assume that children who are together aren't part of a family. A more common scenario involves stepbrothers and sisters, who may not look much like their siblings and obviously won't look like their stepparent. I am often faced with this, as my twins have my brown hair and brown eyes, but my older stepson has blond hair and blue eyes. Since I usually just introduce them as 'my boys,' people will often say that the twins look just like me, but my stepson doesn't. Instead of explaining that he is my stepson, I simply say that he takes after my wife, but it isn't something he should have to hear.
Someone recently went so far as to say to him, 'so what are you, a cousin, friend, neighbor?'
Remember, if a group of kids are together as a family, even if they don't all look alike, then just assume that they are a family...
