By a big head, do you mean in proportion to their bodies? If you mean that, I guess I have a disproportionatly large head, because I'm quite slight, and my daughters make fun, gently, of me, saying that I look like a lollipop.
It's impossible to do something about a large head, except what Ms. O'Donnell has chosen to do, which is get fat enough to balance the head with the body.
If nobody is grabbin' their kids off the street, in horror, then that's somethng, I guess.