There is general agreement that personal vulnerability is often rooted in adverse events and circumstances that occur during the early, formative years of childhood. This chapter explores this idea by examining how the developing child’s milieu affects the developing structures and systems in the social brain. It argues that our ability to communicate our needs to others and to manage our own states of internal distress is critical to our social and emotional well-being and it explains that these abilities are dependent upon the development of the social brain and social cognition during infancy and beyond. In this context, it draws attention to the central role that social cognition plays in allowing the child to develop an understanding of themselves and other people. It explains how the infant brain is highly plastic and dependent for its development upon rich environmental feedback, and it draws attention to research, which shows that abuse and neglect can impair the development of the executive systems in the brain that govern emotion, attention and empathic awareness. The text follows this by looking at attachment and bonding and explains how nature has instilled infants with a strong biological drive to form a physical bond with the mother or primary attachment figure. It outlines these bonds lead to the development of emotional attachments and explains how the creation of secure attachments act as a bulwark against stress and how insecure attachments can generate chronic anxiety and problems related to intimacy and distrust of others in later life. Moving forward, the chapter explains that the development of the self occurs in parallel with the social brain and that the child’s early years’ experiences are critical in shaping their perceptions of self and others. It argues that how we ultimately come to view ourselves is a mirror-image of how we are treated by others and advances the idea that chronic low self-esteem and shame are products of harsh and critical parenting in childhood. The chapter concludes by drawing attention to the emerging science of epigenetics, which shows that significant changes in our environment or personal circumstances can alter the way that our genes are expressed. In doing so, it examines evidence which appears to show that maternal exposure to toxic environments can trigger changes in gene expression in the developing foetus, that shape the body’s response to the triggering phenomena in later life.