Happiness, or sllbjecti~'e Il'ell-beillg, Il'as measllred on a birth-record-based sample of serernl thousand middleaged twins IIsing the Well-Being (WB) scale of the MlIltidimensional Personality Questionnaire. Neither socioeconOlllic staillS, edllcational attainlllell1, family income, marital stallls, nor an indicant of religious cOllllllitmell1 could account for more than abollt 3% ofthe variance in WB. From 44% to 52% ofthe variance ill WB, hOll'ever, is associated Il'ith genetic variation. Based on the retest ofsmaller samples oftll'ins after ill1ervals of 4.5 and IO years, we estimate that the heritability of the stable component of subjective Il'ell-being approaches 80%.Happiness depends. as Naiure shows, less on exterior things than most suppose.-William CowperAre those people who go to work in suits happier and more fulfilled than those who go in overalls? Do people higher on the socioeconomic ladder enjoy life more than those lower down? Can money buy happiness? As a consequence of racism and relative poverty, are black Americans less contented on average than white Americans? Because men still hold the reins of power, are men happier than women? The survey in this journal by Myers and Diener (1995) indicated that the answer to these questions, surprisingly, is "no." These authors pointed out that people have a remarkable ability to adapt, both to bad fortune and to good, so that one's life circumstances, unless they are very bad indeed, do not seem to have lasting effects on one's mood.Vet some people do seem to be happier on average than other people are. Although people adapt surprisingly quickly to both good news and bad, the set point around which happiness varies from time to time apparently differs from one person to another. Myers and Diener considered personal relationships, religious faith, and the "flow" of working toward achievable goals as possible determiners of individual differences in the happiness set point.We had already collected demographic and questionnaire data on a large sample of adults, and it seemed appropriate to try to replicate and perhaps extend some of Myers and Diener's findings. The Minnesota Twin Registry (Lykken, Bouchard, McGue, & Tellegen, 1990) is a birth-record-based registry of middle-aged twins born in Minnesota from 1936 to 1955. We know how far these twins went in school, their approximate family income, their marital status, and their socioeconomic status (SES), based on their occupations. These twins provide an unusually representative sample of the white population (during the 20 birth years searched, fewer than 2% of Minnesota births were to African or Native Americans). Some of the twins Address correspondence to David Lykken, Department of Psychology, University of Minnesota, Minneapolis, MN 55455-0344. did not reach the eighth grade, whereas others have doctorates' they live on farms, in small towns, in big cities, and in foreigl ands; their socioeconomic levels are representative of Minnesota-born adults. METHODA self-rating questionnaire was administer...

Most theories in the areas of personality, clinical, and social psychology predict no more than the direction of a correlation, group difference, or treatment effect. Since the null hypothesis is never strictly true, such predictions have about a SO-SO chance of being confirmed by experiment when the theory in question is false, since the statistical significance of the result is a function of the sample size. Confirmation of a single directional prediction should usually add little to one's confidence in the theory being tested. Most theories should be tested by multiple corroboration and most empirical generalizations by constructive replication. Statistical significance is perhaps the least important attribute of a good experiment; it is never a sufficient condition for claiming that a theory has been usefully corroborated, that a meaningful empirical fact has been established, or that an experimental report ought to be published.

We administered the Multidimensional Personality Questionnaire (MPQ) to 217 monozygotic and 114 dizygotic reared-together adult twin pairs and 44 monozygotic and 27 dizygotic reared-apart adult twin pairs. A four-parameter biometric model (incorporating genetic, additive versus nonadditive, shared family-environment, and unshared environment components) and five reduced models were fitted through maximum-likelihood techniques to data obtained with the 11 primary MPQ scales and its 3 higher order scales. Solely environmental models did not fit any of the scales. Although the other reduced models, including the simple additive model, did fit many of the scales, only the full model provided a satisfactory fit for all scales. Heritabilities estimated by the full model ranged from .39 to .58. Consistent with previous reports, but contrary to widely held beliefs, the overall contribution of a common family-environment component was small and negligible for all but 2 of the 14 personality measures. Evidence of significant nonadditive genetic effects, possibly emergenic (epistatic) in nature, was obtained for 3 of the measures.Until recently, almost all knowledge regarding environmental and genetic causal influences on stable personality traits has come from studies of twins reared together. The findings have been both remarkable and puzzling. On the genetic side, regardless of the trait studied, the intraclass correlation for fraternal, or dizygotic (DZ), twins has approached .25; that for identical, or monozygotic (MZ), twins has approached .50 (Goldsmith, 1983;Nichols, 1978). Application of the simplest genetic model, the Falconer (1960) formula for heritability, [h 2 = 2(R M z -RDZ)], to those results yields a heritability of about .50. This leaves 50% of the variance to systematic environmental influences, measurement error, and temporal instability.Particularly puzzling, and contrary to what many psychologists would predict, is the finding that almost none of the enviThis research has been supported by grants from the University of Minnesota Graduate School, the Koch Charitable Foundation, the Spencer Foundation, the National Science Foundation (BNS-7926654), the Pioneer Fund, and the Harcourt Brace Jovanovich Publishing Company.We thank the following people for the time and effort they have given to testing the twins: Margaret Keyes, Jeff McHenry, Elizabeth Rengel, Susan Resnick, Joy Fisher, Jan Englander, and Ann Riggs. We are indebted to our colleagues and collaborators on the Minnesota Study of Twins Reared Apart project, Elke Eckert and Leonard Heston for their help and advice. We owe special thanks to our colleagues, Greg Carey and Matt McGue, for their valuable biometric advice and assistance. We also thank Jack Darley for his resolute and dedicated support and the Minneapolis War Memorial Blood Bank, Herbert Polesky, Director, for the blood testing.Correspondence concerning this article should be addressed to Auke Tellegen, Department of Psychology, Elliott Hall, University of Minnesota, 75 East River Road...

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As compared with 15 normal controls, " "primary' sociopaths showed significantly less "anxiety' on a questionnaire device, less GSR reactivity to a "conditioned' stimulus associated with shock, and less avoidance of punished responses on a test of avoidance learning. The "neurotic' sociopaths scored significantly higher on the Taylor Anxiety Scale and on the Welsh Anxiety Index." Cleckley's descriptive criteria were used. 24 references.