It is suggested that four factors influence individual development: nature (genes and the physical environment), nurture (the social environment), choice (exercising one's agency), and the ‘shape' of the soul. The first two factors have been examined thoroughly in psychology, while the other two have been largely ignored. However, the studies on identical twins, who have also shared the same environment, show that their traits correlate only to about 50%. Evidently, nature and nurture are insufficient. Out of those four factors nature and the ‘shape' of the soul are the givens responsible for the character. A new born is not a blank slate - certain potentials can be already recognised in infancy. Innate character though, can acquire different forms and be modified throughout life, which makes one's personality. This is where the other two factors, nurture and personal choice, play a role. Turning to development itself, it is possible to distinguish two types: the quantitative and the qualitative.
- . This last one deserves special attention and will be discussed in the following chapter.