Research Paper (undergraduate) from the year 2013 in the subject Psychology - Developmental Psychology, grade: B, ( Atlantic International University ) (Social Sciences), course: D.psych (Clinical), language: English, abstract: There has been a vigorous debate in recent time, about heredity versus environment and how they coalesce to create personalities, behaviors, and psychopathology that appeared unique to each person and influenced their developmental process. This study explores and used different methodological approach to lifespan development to measure and analyze the interplay of genes and environments on human behavior and underline how the interaction contributes to behavioral changes and continuity. The study planned to increase our knowledge and understanding of the interaction between heritable and ecological factors in the path of behavioral growth and patently recognize etiological mechanism that support the assumption that a particular hereditary or environmental condition ultimately lead to behavioral feature and changes during development. The study used the accessible materials on lifespan development to understand the continuous source of person uniqueness in personality development. Finally, citing evidence from various multidisplinary studies, the article concluded that shared environment significantly influenced human behavior but decline with age and that the strong interaction between the two factors formed the basis of who we are and how we behave.