Final answer:
By the age of 20, people have lost some of their taste receptors.
Step-by-step explanation:
Taste buds have a life cycle of ten days to two weeks, so as people age, they gradually lose taste receptors. By the age of 20, people have lost some of their taste receptors. The decline in taste receptors continues throughout life, making certain foods taste less flavorful and enjoyable as people get older.