What causes grooves in the tongue?

Geographic tongue. Geographic tongue, an inflammatory condition of the tongue affecting approximately 2% of the population, is characterized by discolored regions of taste buds or sometimes even cracks in the surface of the tongue. The condition is usually chronic, and frequently manifests after eating any of a range of exacerbating foods, or during times of stress, illness, or hormonal surges (particularly in women.
Depends. Grooves in the sides of our tongue can come from the pressure of your tongue against the insides of your teeth. Grooves down the middle are probably hereditary.