The answer to the riddle is "obesity."
- "I grow not from birth, but from what you choose": Obesity is influenced by dietary choices rather than being something one is born with.
- "From sugar and grease and too many stews": These are often associated with foods that contribute to weight gain and obesity.
- "I'm not a disease, but I bring them near": Obesity itself is not classified as a disease, but it is linked to many health issues (like diabetes and heart disease).
- "And though I'm soft, I cause much fear": Obesity can lead to health fears and concerns, and it can also be associated with a soft body composition.
So, the answer is obesity.