Demeter was born it. There is no why, she just is.
Grain and fertility.
You have your gods mixed up; the goddess of fertility was Aphrodite and the goddess of grain and harvest was Demeter.
Demeter is the goddess of fertility, and grain
Immortal: she is the goddess of grain and fertility.
If you mean Demeter, she is a Greek goddess of grain, fertility, and harvest and is the mother of Persephone.
Demeter was the Greek goddess of grain & fertility. Her Roman counterpart was Ceres.
Demeter is not named Ceres. Demeter is the Greek goddess of of agriculture, grain, and bread, the prime sustenance of mankind. Ceres is the Roman goddess of agriculture, grain crops, fertility and motherly relationships identifed with Demeter.
He does have a mother. In fact his mother's name is Demeter, the goddess of agriculture, grain, and fertility.
Demeter cult titles includes Sito (she of the Grain, the giver of grain) and Thesmophoros (bearer, giver of divine order, law-bringer). As a goddess did not have duties. She was the goddess of grain, the harvest, who presided and the fertility of the earth.
Demeter was the Greek goddess of agriculture.
The Greek goddess of grain is Demeter.
Demeter is the Greek goddess of agriculture (particularly grain), fertility, the seasons, and the harvest. She is daughter of Kronos and Rhea, and mother of Persephone. Her symbols are a torch, a sheaf of wheat, or barley.