Department of Psychology
Department of Psychology

John C Loehlin

Professor EmeritusPh.D., University of California, Berkeley

John C Loehlin


Human behavior genetics, multivariate statistics, and structural modeling


John Loehlin is Professor Emeritus of Psychology and Computer Science at The University of Texas at Austin. He was born in India in 1926 of U.S. missionary parents, and attended mission schools in that country. He received an A.B. in English from Harvard in 1947, and a Ph.D. in Psychology from the University of California at Berkeley in 1957. He was on active service in the U.S. Naval Reserve in 1951-53 during the Korean war.

He taught at the University of Nebraska from 1957 to 1964, before moving to The University of Texas, where he has remained since, except for a visiting semester at the Institute for Behavioral Genetics at the University of Colorado and a year at the Center for Advanced Study in the Behavioral Sciences in Palo Alto. He has served as president of the Behavior Genetics Association and of the Society for Multivariate Experimental Psychology. He received the Dobzhansky Award from the former in 1991. He is married and has two children.

His research has chiefly focused on the genetic and environmental contributions to individual differences in normal human personality traits and abilities; he has also been concerned with racial differences and with computer modeling. He has been involved in several twin family, and adoption studies, including the National Merit Twin Study with R. C. Nichols, an Israeli family study of spatial abilities with S. Sharan and R. Jacoby, and the Texas Adoption Project with J. M. Horn and L. Willerman.

Major Publications

Loehlin, J. C. (1968). Computer models of personality. New York: Random House.

Loehlin, J. C., Lindzey, G., & Spuhler, J. N. (1975). Race differences in intelligence. San Francisco: Freeman.

Loehlin, J. C., & Nichols, R. C. (1976). Heredity, environment, and personality: A study of 850 sets of twins. Austin, TX: University of Texas Press.

Loehlin, J. C. (1987). Latent variable models: An introduction to factor, path, and structural analysis. Hillsdale, NJ: Erlbaum.

Loehlin, J. C. (1992). Genes and environment in personality development. Newbury Park, CA: Sage.

Loehlin, J. C., Medland, S. E., Montgomery, G. W., and Martin, N. G. (2005). Eysenck's Psychoticism and the X-linked androgen receptor CAG polymorphism in additional Australian samples. Pers. Indiv. Diffs., 39: 661-667. PDF

McFadden, D., Loehlin, J. C., Breedlove, S. M., Lippa, R. A., Manning, J. T. and Rahman, Q. (2005). A reanalysis of five studies on sexual orientation and the relative length of the 2nd and 4th fingers (the 2D:4D ratio). Archiv. Sex. Behav., 34: 341-356.PDF

Loehlin, J. C., Jönsson, E. G., Gustavsson, J. P., Stallings, M. C., Gillespie, N. A., Wright, M. J., and Martin, N. G. (2005). Psychological masculinity-femininity via the gender diagnosticity approach: Heeritability and consistency across ages and populations. J. Pers., 73: 1295-1319.

Loehlin, J. C., Neiderhiser, J. M., and Reiss, D. (2005). Genetic and environmental components of adolescent adjustment and parental behavior: A multivariate analysis. Child Devel. 76: 1104-1115.

Loehlin, J. C., McFadden, D., Medland, S. E., and Martin, N. G. (2006). Population differences in finger-length ratio: Ethnicity or latitude? Archiv. Sex. Behav. 35: 739-742. PDF

Harden, K. P., Turkheimer, E., and Loehlin, J. C. (2007). Genotype by environment interaction in adolescents' cognitive aptitude. Behav. Genet. 37: 273-283.

Loehlin, J. C., Horn, J. M., and Ernst, J. L. (2007). Genetic and environmental influences on adult life outcomes: Evidence from the Texas Adoption Project. Behav. Genet. 37: 463-476. PDF

Loehlin, J. C. (2007). The strange case of c2 = 0: What does it imply for theories of behavioral development? Res. Hum. Devel. 4: 151-162.

Career Overview

John Loehlin’s undergraduate studies, partly under the auspices of the US Navy’s V-12 and NROTC officer training programs during World War II, took place at the colleges of Wooster and Baldwin-Wallace in Ohio, and Harvard University; from the last he graduated with an AB in English in 1947. After a brief stint in advertising, he returned to academic life, and with a two-year interruption for Navy service during the Korean War, obtained a PhD degree in 1957 from the University of California at Berkeley. His dissertation research, under the supervision of Richard S. Crutchfield and Donald MacKinnon,was a factor-analytic study of the influence of different activities on the apparent length of time. During his Berkeley days he served as a Teaching Assistant in an Introductory Psychology course, as a Research Assistant to Warner Brown in an experiment on the effects of visual feedback on motor skill learning, and as a Research Assistant at the Institute for Personality Assessment and Research, where his duties included managing their extensive data base.

Following his PhD, he had two job offers. One was as a Research Assistant with Raymond Cattell at the University of Illinois, and one was a position in the Psychology Department at the University of Nebraska, teaching courses in Personality. He elected the latter, but remained on good terms with Cattell over many years.

At Nebraska, Loehlin developed the two main themes of his later research: behavior genetics, with a main focus on personality, and computers, beginning with the construction of a computer program simulating human personality, which was dubbed Aldous (in honor of the author who described a Brave New World). During that time he also met and married Marjorie Leafdale, of the English Department there.

Loehlin’s interest in the behavior genetics of personality led to a conversation and later a collaboration with Steven G. Vandenberg, then at the University of Louisville. Attendance at a conference hosted by Vandenberg on analyzing twin data resulted in discussions with Robert Nichols, then at the National Merit Scholarship Corporation, who was gathering extensive data on identical and fraternal twins from among the roughly 600,000 U.S. highschool juniors who took the National Merit Scholarship test in 1962. The discussions with Nichols led to a visiting appointment at the National Merit Scholarship Corporation at Evanston, Illinois in the summer of 1967, and later to a book with Nichols: Heredity, Environment, and Personality: A Study of 850 sets of twins (1976, University of Texas Press). The main results of this study were (1) the unsurprising finding that both the genes and the environment contributed to individual differences in personality, and (2) the (at the time) very surprising finding that the environment involved was not the family environment that the twins shared, but the environments experienced by them individually.

Meanwhile, Loehlin’s interest in computer simulation led to an invitation to attend a summer institute on the computer simulation of cognitive processes at the RAND Corporation in Santa Monica, California, led by Allen Newell and Herbert Simon. His specific interest in simulating personality later resulted in a book describing his and others’ work on this topic, Computer Models of Personality (1968, Random House).

In 1964, Loehlin moved from the University of Nebraska to the University of Texas at Austin, for a visiting year which became a permanent appointment when the professor he was replacing decided to stay at the university he was visiting. Loehlin’s joint appointment in Psychology and the Computation Center (and later the Computer Science Department) reflected his joint interests in the psychology of personality (specifically, the genetic contribution to individual differences in personality and intelligence) and computer science (specifically, artificial intelligence and the simulation of psychological processes).

In 1971-72, Gardner Lindzey, J.N. Spuhler, and Loehlin spent a year in Palo Alto, California, at the Institute for Advanced Study in the Behavioral Sciences, to work on a book summarizing existing knowledge about racial and ethnic differences in performance on IQ tests. This eventually resulted in a book Race Differences in Intelligence (1975, W. H. Freeman), which attempted to provide a balanced review of the evidence on this emotionally fraught topic.

At about the same time, Loehlin’s Texas colleagues Joseph M. Horn and Lee Willerman decided to seek funding for a study of genes and environment in adoptive families, and invited Loehlin to join them. They had obtained the cooperation of the Methodist Mission Home in San Antonio, an institution where unwed mothers came to spend the later portion of their pregnancies before relinquishing their infant to an adoptive family. The Home maintained extensive records on the unwed mothers, including IQ and personality tests conducted by an affiliated psychologist. The Texas Adoption Project, as it came to be called, located and tested members of some 300 families who had adopted a child from the Methodist Mission Home. These represented adoptions occurring between 1963 and 1971; the children averaged about 8 years old when they, their adoptive parents, and any other adopted or biological children in the family were assessed with age-appropriate IQ and personality tests and ratings. A follow-up testing of the children after 10 years, later interviews with many of the adoptive parents, and a final follow-up by mail in the early 2000s when the adoptees were in their 30s and 40s, provided data for looking at genetic and environmental causes of resemblance over time among the adoptees and members of their families. Again, genes and individual experiences played the major roles, and the effects of sharing a family environment were modest: genetically unrelated individuals growing up together in the same family were nearly as different as members of the same population paired at random. The results of this 30-year study were published in some 20 articles in professional journals and a book, Heredity and Environment in 300 Adoptive Families: The Texas Adoption Project (Horn & Loehlin, 2010, Transaction Press).

Loehlin’s contributions included textbooks. In the course of investigating methods to extract and represent structures inherent in the large amounts of data in the various studies he was involved in, Loehlin extended his interest in computer modeling, and one result was a book entitled Latent Variable Models: An Introduction to Factor, Path, and Structural Analysis published by Erlbaum, a book that has now gone through four editions (1987 to 2004), with a fifth under consideration. On the behavior genetics side, a brief introductory book on Genes and Environment in Personality Development appeared in 1992 (Sage). On personality more generally, Loehlin assisted Martin Manosevitz in updating Hall and Lindzey’s Theories of Personality (as Introduction to Theories of Personality, 1985, Wiley).

Loehlin has brought a behavior-genetic perspective to a number of broad reviews, such as that on intelligence by a task force headed by Ulric Neisser (1996, American Psychologist), and one led by Stephanie Sherman for the American Society of Human Genetics to address recent developments in human behavioral genetics (1997, American Journal of Human Genetics). A general review with Thomas Bouchard, Jr., on genes, evolution, and personality (2001, Behavior Genetics) has been widely cited. He has also contributed to chapters in a number of handbooks—of Personality (Cattell. 1977; Pervin, 1990), of Intelligence (Sternberg, 2000), of Behavior Genetics (Kim, 2009); and, with Texas colleagues, to Annual Review chapters on behavior genetics in 1971 and 1988.

Supplementary to the major threads of Loehlin’s research are a number of papers addressing the effects of sex hormones—mostly with collaborators, including Dennis McFadden of the University of Texas, Nick Martin and Sarah Medland of the Queensland Institute of Medical Research in Australia, M. C. Stallings of the University of Colorado, and E. G. Jönsson and J. P. Gustavsson of the Karolinska Institute in Stockholm.

In more recent years, Loehlin has developed an interest in the so-called “General Factor of Personality,” resulting in a half-dozen papers, some with collaborators such as Nick Martin in Australia and Lew Goldberg in Oregon, papers addressing such questions as the heritability of a general personality factor (substantial), or what happens to other factors if it is first removed (not much).

Loehlin’s contributions have been recognized by various scholarly organizations. He has served as president of the Society for Multivariate Experimental Psychology founded by Raymond Cattell, and of the Behavior Genetics Association. The latter gave him its Dobzhansky award for a distinguished research career in 1991, and held a Festschrift in his honor at the 2011 BGA meetings in Newport, Rhode Island. The International Society for Intelligence Research has chosen him to receive their 2015 research career award.

Finally, in an entirely different vein, Loehlin is the author of two books of (mostly) light verse: Verses of a Young Man, a recently published collection of verse written when he was in his 20s, and Verses of Later Years, consisting predominantly of occasional verse from more recent times.


Loehlin, J. C.  (1968). Computer models of personality.  New York:  Random House. 

Loehlin, J. C., Lindzey, G, and Spuhler, J. N. (1975).   Race differences in intelligence.  San Francisco:  W. H. Freeman.

Loehlin, J. C. & Nichols, R. C.  (1976). Heredity, environment, and personality: A study of 850 sets of twins.  Austin, TX:  Univ. of Texas Press.

Loehlin, J. C., Lindzey, G, and Spuhler, J. N. (1978).   Intelligenza, genetica, ambiente.  Rome:  Armando.  (Italian translation of Race Differences in Intelligence.)

Hall, C. S., Lindzey, G., Loehlin, J. C., and Manosevitz, M. (1985).  Introduction to theories of personality.  New York:  Wiley.

Loehlin, J. C. (1987).  Latent variable modelsAn introduction to factor, path, and structural analysis.  Hillsdale, NJ:  Erlbaum.

Loehlin, J. C. (1992).  Genes and environment in personality development.  Newbury Park, CA: Sage.

Loehlin, J. C. (1992).  Latent variable modelsAn introduction to factor, path, and structural analysis. (2nd ed.) Hillsdale, NJ: Erlbaum.

Loehlin, J. C. (1998).  Latent variable modelsAn introduction to factor, path, and structural analysis. (3rd ed.) Hillsdale, NJ: Erlbaum.

Loehlin, J. C. (2004).  Latent variable modelsAn introduction to factor, path, and structural equation analysis. (4th ed.) Hillsdale, NJ: Erlbaum.

Horn, J. M, and  Loehlin, J. C. (2010).  Heredity and environment in 300 adoptive families: The Texas Adoption Project.  New Brunswick, NJ: Transaction. 


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