A child's heredity consists of genes that are passed along from the parents. What do these genes primarily determine?

The primary role of genes inherited from parents is to determine physical characteristics, which is why physical appearance is the correct choice. Genes influence traits such as eye color, hair type, height, and other physical features. While it's true that heredity can play a role in certain aspects of social skills and intellectual abilities, the foundation of a child's physical attributes is strongly linked to their genetic makeup.

Additionally, brain development is influenced by a combination of genetic and environmental factors. Genetics can set certain parameters for brain structure and function, but interaction with the environment significantly shapes how the brain develops and functions over time. Therefore, while genes contribute to the potential for brain development, they do not solely determine it, unlike the more direct impact they have on physical appearance.