This article identifies the physiological, neurological, and psychological determinants that arise from constraints imposed by both genetic and environmental factors, originating human behaviours. The determinants, called Ego Selves, that organise the phenomena that Eric Berne classified, structured, conceptualised, and defined to mould transactional analysis and design instruments to assist professionals and patients to adjust behaviours, are analysed. A different form of presenting the adapted Child, differentiating it from Berne’s model where the adapted Child is shown as a part of the natural Child, is presented. Parent-Adapted Child, and the Adult ego states, adjusting their manifestation and organization to the physiological development of their corres-ponding ego self, are identified, proposing that the Adapted Child is a part of the Parent ego state. Contamination is reviewed and adjusted for cons-istency between cause and effect, identifying that the contaminated ego state is the Parent ego state, creating a delusion based on injunctions that generate an illusion in the adapted Child portion of it which in turn causes the natural child’s emotional reaction, considerably limiting the Adult ego state's capabilities to intervene. Script analysis is reviewed and organised indicating that the script is a life plan initiated at conception and ending at death, and that it is indispensable for survival, having adequate and inadequate segments that may limit lifespan and quality of life. Occurrences, neurophysiological factors, and memories involved in their development and implementation are also identified. Suggestions and examples for the integrated development of intervention strategies and tactics to adjust behaviours and fulfil contracts are presented in the corresponding section.