Ideas About How the Onset of Stuttering Occurs Have Changed

Ideas about how the onset of stuttering occurs have changed in that:

A) we now think that it is all genetically controlled
B) we used to think it began in a uniform fashion but now we have evidence that there is much variability in several aspects of onset
C) we now know that, most typically, stuttering begins as a mild disorder
D) our ideas about the onset of stuttering have not substantially changed.