It is possible to guess someone's age with relative accuracy based on factors like their skin elasticity and clarity, the fluidity of their movements, and even their name. In conversation, asking indirect questions can help establish a timeline that is helpful in guessing someone's age.
When a situation calls for estimating a person's age without asking them directly, there are several ways to proceed. Using only the person's name, it's sometimes possible to guess which decade they were born based on naming trends. In conversation, ask how old the person's parents are, what year they graduated from high school, or if they remember a certain event or trend. Asking someone if they have older or younger siblings often leads to discussion about age.
Physically, skin is a good predictor of age. As skin ages, it becomes drier and loses its elasticity. This leads to fine winkles around the eyes and mouth and drooping of the skin around the chin, cheeks and neck. Skin also becomes rougher as benign bumps and growths appear. Sun exposure can cause premature aging of the skin, so these signs appear more quickly in those who spend a lot of time in the outdoors. Flexibility is also diminished as humans age, so a younger person's movement appears more fluid than those of an older person.