Many individuals are born with defects due to genetic factors. Some such defects occur because the child inherits a defective gene, or genes from the parents. Others are caused through mutations- spontaneous changes that occur to a gene or chromosome. Environmental factors affecting the foetus during the uterine development may also cause defects. If, during pregnancy, a woman smokes, consumes alcohol or other drugs, or suffers dietary deficiencies, the developing foetus may be adversely affected. About one in every seven hundred births is Down syndrome baby. Down syndrome is now more frequently referred to as trisomy- 21, as new individuals...
or heredity, but never the factor that is most important. Many of the characteristics displayed by humans are due to the interaction of both heredity and environment. The height to which an individual grows for example, is a case where heredity plays a role in the determination of the end result. If a person has tall parents, it is more likely that he or she too, will also be tall. In addition, growth is affected by environmental factors like nutrition. The question of that of the two factors- heredity or environment is the more important has no simple answer.