The union between the mother’s egg and the father’s sperm determines what the child will be like.
A baby develops from the union between the mother’s egg and the father’s sperm. This union determines what the child will be like, such as how tall he or she will be, what color the eyes will be, and what the shape of the nose and mouth will be. How the parents pass these characteristics to their child is called genetics.
Each cell in the human body contains 48 structures called chromosomes. The reproductive cells, that is, the male sperm and the female egg, each contain only 23 chromosomes – half as many as all other cells in the human body. Each chromosome is made up of many genes, and it is these genes, half of which come from the father and half from the mother, that combine to determine what a person will be like.
Boy or Girl?
Some families would rather have sons than daughters, and in parts of Africa women are blamed if they do not bear sons. Some wives have been divorced for not producing a son. In actual fact however, it is the father, not the mother, who determines whether the baby is a boy or girl.
How? A sperm contains 22 regular chromosomes and one sex chromosome, either X (female) or Y (male). All eggs contain 22 regular chromosomes and one sex chromosome, which is always X (female). If a sperm with a Y chromosome fertilizes the egg, the baby will be a boy, and if a sperm with an X chromosome fertilizes the egg, the baby will be a girl.
Children inherit other characteristics from their parents besides height and the color of their eyes. Certain physical or mental disorders can also be passed from one generation to the next. Among Africans, or people of African descent, two well-known conditions that can be passed from parents to their children are sickle cell disease and albinism.