Just as a circle has no beginning and no end, true expressionlessness has no start and conclusion. When expertly performed, it feels natural and inherent, as though the model was born with such a soulless facial form.
Perhaps their parents did not approve of such an appearance and disowned them. Perhaps they did not perform well in job interviews because the employers were frightened by such stoicism, so they lapsed into an otherwise unemployable state. However, this is all tangential to fashion.
Katherine exhibits the requisite blankness of effective fashion. It is the featureless stare ahead that does not detract from the vivid tones of the white coat, in all its blinding glory, and colourful stethoscope.