Following his book The Kindness of Human Milk and drawing upon the plethora of relevant published research papers, the author describes how a fundamental misunderstanding of the immunological significance of maternal milk has led to the inevitable development and spread of Western Diseases. Human neonates are altricial, relying on maternal milk for several months. After an embryo has already learned to treat maternal antigens as ‘self’ during its gestation, maternal milk provides an immunologically safe food resource while the gut immune system is maturing. If this were not the case, every morsal consumed by the newborn would be likely to set off an immune reaction until the immune system became overwhelmed. The human gut immune system matures at around four to six months from birth. The widespread damage to health caused by early feeding of formula milks is explored and the consequences are described in some detail.