The behavioral consequence of ethanol odor exposure appears to be cumulative. Mean composite reflexive sniffing index values (± sem) of adolescent observers as a function of the number time periods in development during which ethanol experience occurred (i.e., fetal and/or adolescent). Note the graded effect with increasing experience. No ethanol experience = free choice and pair-fed animals with water experience in adolescence. One ethanol experience = all animals having received one developmental time point of experience with ethanol (i.e., free choice and pair-fed observer animals with ethanol odor experience in adolescence and prenatal ethanol observer animals with water experience in adolescence. Two ethanol experiences = observer animals receiving both prenatal and adolescent ethanol experience.