The ancient psychological debate, which aspects of our mind are primarily formed by genetics and heredity, and which aspects are mainly formed by our experience of objects and events in our environment, is being renewed by developments in the field of prenatal psychology. A recent book by Annie Murphy Paul, with the title Origins: How the Nine Months Before Birth Shape the Rest of Our Lives, explores how everything from our taste in music to our body weight is influenced neither by our gene pool, nor by our life experiences, but rather by our prenatal encounters.
The fact that babies can hear, and hear well, long before birth, and through an inch or two of maternal flesh, means that children are born having already heard much: music, voices, etc. Psychologists have long known that infants are able, upon birth, to recognize the voices of their mothers. But it is now clear that familiarity with, and tastes in, music are also so formed.
Separately, experiences in the womb also act as switches, turning on or off various individual genes. Thus the diet of the mother with shape the metabolism of the child. An adult's weight problem may due, not his psychology and environment, nor strictly to his genes, but rather to events which activated some of his genes, but not others, in the nine months he spend in the womb.
The field of prenatal psychology will cause much re-thinking of various sub-disciplines within traditional psychology and psychiatry.