I was not able to find any studies that indicated whether people skip Kegan stages, regress in stage, or exhibit characteristics of other stages, or other psychometric instruments that decompose into Kegan stages with factor analysis. The concept of adulthood has legal and socio-cultural definitions. Other enjoyable insights from the Evolving Self for me: How and why we age. Ah, I think I misunderstood about the stages then. In Adult development stage, hormonal changes also affect their reproductive and sexual physiology, but these changes are not as extreme as those Adult development stage by women.