The smell of mother helps in the growth and development of a newborn child's olfactory centres. This is used in the process of bonding and is closely related to the way that the rest of the brain wires itself up to perceive the rest of the world. Just as I've been saying for years – reality itself is the force behind congitive development!
Now, the burning question is – should Kerry go "au naturelle" prior to the birth so that the twins can smell her "natural" body odours ;-) maybe even ahave a curry or two? Or should she dose up on the Chanel #5?