How genes are passed down from each generation
Natural selection is a great influence on the traits that are passed down to generations. Cheetahs have passed down genes that improve their camouflage and make them faster runners. The cheetahs that are easier to catch by predators don't normally live long enough to reproduce and pass their genes which is good for the species, making it stronger.
Sexual reproduction improves the genetic variety in species and often increases survivorship in the offspring through gametes. Gametes contain DNA which carry important characteristics for the offspring. In the animal kingdom the two "best" animals of a group of species will mate and pass both of their genes down to create a better offspring.
Traits like fur color greatly improve survivorship.
DNA is completely random.
Certain traits in cheetahs can improve their agility, as well.
Dominant and Recessive Traits
When genes are passed down from the parents they will be dominant or recessive traits. A dominant gene will override the recessive gene when it comes to fur color and other traits. However, the genes that are submitted during conception can be completely random, narrowing down numerous characteristics.