I can, and have, covered the entire spectrum when it comes to my own children, who have modeled professionally since they were little. (The upside, or is that downside, of having a professional photographer for a mum) The difference in my attitude is based on a couple of different things.
Where was the image taken?
If the child was someplace private or if a photographer seemed to be taking an overly eager interest in my child, then there would be cause to worry. If an image of my child, taken through the window of our home, for example, suddenly showed up in advertising for anything - then there would be a real problem.
What is the image being used for?
Was there a model release?