Gali, he is asking about SimPE, not the Enhancer. You don't even use SimPE.
Jysudo, the Skintone range comes from the parents' genetics. If you have an S1 mother and an S4 father, the children will have a range of S1-S4. It is possible for the children to have any skin tone. However, if the parents skintones are closer together, say S1 and S3, then the children can have any skintone from S1-S3. When they reproduce, however, they will only pass on to their children the skintone they express.