General factors which would influence and tend to favour mandibular prognathism are as follows:

• Increased height of the ramus

• Increased mandibular body length

• Increased gonial angle

• Anterior positioning of the glenoid fossa

•Decreased maxillary length

• Posterior positioning of the maxilla in relation to the cranium

• Prominent chin button

•Varying soft-tissue contours

Source- textbook of oral pathology Shafers and Google images