Mother’s breastmilk is not sweet.
The first set of foods for six months old babies are not sweet. Plain biscuits, mashed potato, carrot and squash.
In case no sweets will be introduced, the baby will grow up loving all the bland foods available.
As the baby grow, the commercial milk formula become sweeter and yummier. People around him also start giving him jellies, soft candies and other sweet stuffs.
After getting used to sweets, the baby starts turning down bland tasting foods. Try giving a bland milk and he will throw the bottle away. He will just taste a mashed potato but never eat it.
Those statements are purely based on my observations. Do you observed the same things?
Are we really born with a sweet tooth? Are we really born to love sweets? I think we are not born to love sweets. We are trained to love sweets. No one gonna have a love for sweetness if pure sugar was not invented. The only thing that is likely to happen is the love for sweet and nutritious fruits.