  We build on the empirical finding that a human being's mental age is normally
distributed around the chronological age. This opposes the frequent societal
assumption "mental = chronological" which is known to be false in general but
entertained for simplicity due to lack of methodology; hence disregarding that,
f.e., people of different chronological ages can be much closer in their mental
ages. As a quantitative approach on a scientific basis, we set up a general
formula for the probability that two individuals of given ages are mentally
within a certain range of years and investigate its implications i.a. by
critically analyzing popular assumptions on age and computing statistical
expectations within populations.
