Genetic information is passed on from a parent to a child via the process of meiosis. When the cells divide, the four games produced are all different. Even though they all have the same number of chromosomes and carry information about the same characteristics, the specific information varies. For example, a homologous pair of chromosomes carry the gene for eye colour, where one chromosome caries the gene and holds information for a for blue eye colour and the other specifies brown eyes. When this cell forms gametes, half will have the information carrying for blue eyes and the other half will have the information for brown eyes. So, for Sarah and Helen to have blue eyes, it is clear that they both have the gene that carries information for their mother's blue eye colour.
