Many people wonder how and why eggs develop into chicks. You might wonder why eggs from the supermarket don't grow and hatch when incubated. The male chicken or rooster makes the difference.

The rooster must be present for an egg to be fertilized. Most eggs that you buy at the supermarket are from hens that are raised without a rooster being present. Roosters are not necessary at egg farms where eggs are produced for consumption. Eggs for incubation are grown at special farms called breeder farms where roosters are present with the hens.