A number of readers of this post think that Pearl has authored the definitive opinion on causality. However entertaining this may be, it is flawed. That post is a highly rated answer, and in that light the downvotes for this post were mistakenly awarded. A better approach to this arises from mechanics, i.e., from physics as epitomized by Newton's laws, e.g., "For every action, there is an equal and opposite reaction," in that we refer to a cause as an 'action' and an effect as a 'reaction'. Note the atemporality correctly implied by the phrase 'equal and opposite;' that is, effect is not subordinate to cause, they are equal, simultaneous and opposite.
Why atemorality? To begin with "Statistics means never having to say you’re certain”. Statistics can be used to screen for probable causes, but more is needed for a conviction regarding causality, both legally, and in experiments. Taken alone, statistical arguments do not reduce to cause and effect because the Sir Arthur Conan Doyle criterion, "When you have eliminated the impossible, whatever remains, however improbable, must be the truth" does not adjudicate between multiple improbabilities, and neither does statistics. Furthermore, naive attempts at defining causality based upon untested assumptions lead to outright rediculous statements. For example, in the Merriam Webster Dictionary one reads with dismay that Causality is "the relation between a cause and its effect or between regularly correlated events or phenomena." True enough, language is fluid and people use words without worrying about whether those words are used self-consistently, and if the reader is one of those, then my concern about defining causality in a self-consistent fashion is irrelevant, and subjects like Resolving the black hole causality paradox cannot be understood, because the definition of causality used is strict, unambiguous, and uninterpretable using sloppy definitions of causality.
In that light, we turn to physics to investigate causality, and if we do not, we will never sort out just how confusing causality is. Regarding atemporality, there are those who claim, without proof, that cause must precede effect because that "seems" reasonable. Is it? "The arrow of time" is ambiguous at the quantum level, and effects can precede causes, e.g., see The arrow of causality and quantum gravity. If a cause is persistent in time, an effect may have temporal duration, but the effect may still precede the cause in temporal sequence at the quantum level, the durations can be in negative time, and the clock can run backwards. It takes a while staring at Feynman diagrams to understand why this is the case, e.g., "Feynman used Ernst Stueckelberg's interpretation of the positron as if it were an electron moving backward in time.[3] Thus, antiparticles are represented as moving backward along the time axis in Feynman diagrams."
The OP is correct from a physical sciences point of view. In simplest form, the possibility of a physical time-independent view of causality is at the basis of the deductive-nomological (D-N) view of scientific explanation, considering an event to be explained if it can be subsumed under a scientific law. In the D-N view, a physical state is considered to be explained if, applying the (deterministic) law, it can be derived from given initial conditions. (Such initial conditions could include the momenta and distance from each other of binary stars at any given moment.) Such 'explanation by determinism' is sometimes referred to as causal determinism.
Getting a bit more complete about this, one would include Hempel's inductive-statistical model to form a scientific explanation, which link offers a more complete discussion of causality.
As for the problem at hand, age can be related to experience, but the relationship is not simple, moreover, brain function at different ages is different (time demarcation dilates with age). Experience as a modifier of behaviour is quite variable, and just because a cohort in a certain territorial and temporal sense may have similar historical experiences does not imply that any behaviour resulting from those experiences can be extrapolated to other cohorts without fear of contradiction. With respect to a controlled trial, the commonality of experiences is an uncontrolled variable that introduces an unknown and unexplored amount of spurious correlation into any binary comparison such that any difference found should not be thought of as revealing a probably causal linkage. Moreover, a probable cause, when found, would only constitute a suspicion and not something one can state with conviction; it is at best a working hypothesis not a best conclusion. Convictions concerning causality should only be drawn from a body of evidence that is inclusive enough for those convictions to be without reasonable doubt. That is not the case for the question above for which there is not enough information to claim any causal relationship beyond a coincidental context from cohort grouping. One can, indeed, formulate so many hypotheses, for example, that the evolution of generosity with age is modified by cultural/historical epoch experience, that no firm conclusions can be drawn from the problem as stated.
