Genetics!
It is a well-established fact that children tend to take on the same physical characteristics as their parents. Even though it has been suggested that one day we might be able to change the DNA of an unborn child to give it a certain trait, this kind of technique is still a long way off.
Despite what this young mother may believe, the size of a child’s nose cannot be altered by having any number of rhinoplasty procedures. It’s possible that she’s not quite ready to have a family just yet, at least not before she finds out the whole story.