Attachment is an interesting topic. Dan Siegel has some good videos on YouTube about how a child's experiences with his mother cause his brain to develop, and how brain structure is not permanent because of neuroplasticity. The way a person forms attachments to others is influenced by synaptic connections in his brain. New connections can be made at any point in his life which can change the integration of his brain hemispheres. The outcome is that he may relate to people differently.