Nature and nurture are intertwined- gene expression is one way to understand at one level. Prenatal and infant development are both heavily affected by environmental factors. For example, a fetus growing in an environment containing a lot of teratogens (alcohol, viruses, drugs, etc. ) will result in abnormal developments in the womb. There are about one hundred thousand industrial chemicals in our environment, many of which can be measured in the bodies of fetuses before they have even been born. A mother"s stress and emotional state has an effect on the development on the developing fetus. Birth weight, cognitive and physical development can all be affected by the mother"s their neurological development. (ospitals are encouraging parents to engage in (cid:498)kangaroo care(cid:499)- increase the amount of skin to skin contact. emotional climate. If a person grows up in a family that fights a lot or a society that systematically oppresses then these things converges on the mother and therefore the developing fetus.