Twin analysis of odor identification and perception.

Findings from the first twin analysis using the University of Pennsylvania Smell Identification Test (UPSIT) and a phenyl ethyl alcohol (PEA) threshold detection test are presented. A genetic influence on odor identification was suggested for males, but not for females, consistent with previous twin research on physical measures. In addition, females scored significantly higher on the UPSIT than males. A curvilinear age trend for odor identification was detected for males, but not for females. In contrast, neither genetic, age, nor gender effects were suggested for PEA sensitivity. Performance on the olfactory tests was unrelated to scores on standard measures of intelligence.