Before a child is born, we can predict many of the biological characteristics of the child by observing the parents. This is because we know the laws of heredity.

For example, if one parent has brown eyes and the other has blue eyes, the child will be brown-eyed. If neither parent has any brown pigment in the ring around the pupil, the child also will have pure blue eyes. If one of the parents has curly hair, then the child will have an even chance of having curly hair.