Last updated on: 3/26/2013 | Author:

William R. Rice, PhD Biography

Professor of Ecology, Evolution, and Marine Biology at the University of California at Santa Barbara
Pro to the question "Is Sexual Orientation Determined at Birth?"

“Pedigree and twin studies indicate that homosexuality has substantial heritability in both sexes, yet concordance between identical twins is low and molecular studies have failed to find associated DNA markers. This paradoxical pattern calls for an explanation. We use published data on fetal androgen signaling and gene regulation via nongenetic changes in DNA packaging (epigenetics) to develop a new model for homosexuality. It is well established that fetal androgen signaling strongly influences sexual development. We show that an unappreciated feature of this process is reduced androgen sensitivity in XX fetuses and enhanced sensitivity in XY fetuses, and that this difference is most feasibly caused by numerous sex-specific epigenetic modifications (‘epi-marks’) originating in embryonic stem cells. These epi-marks buffer XX fetuses from masculinization due to excess fetal androgen exposure and similarly buffer XY fetuses from androgen underexposure. Extant data indicates that individual epi-marks influence some but not other sexually dimorphic traits, vary in strength across individuals, and are produced during ontogeny and erased between generations. Those that escape erasure will steer development of the sexual phenotypes they influence in a gonad-discordant direction in opposite sex offspring, mosaically feminizing XY offspring and masculinizing XX offspring.”

Cowritten with U. Friberg and S. Gavrilets, “Homosexuality as a Consequence of Epigenetically Canalized Sexual Development,” Quarterly Review of Biology, Dec. 2012

Involvement and Affiliations:
  • Professor of Ecology, Evolution, and Marine Biology, University of California at Santa Barbara
  • Resident Scholar, University of Chicago, 1995
  • Presidential Endowed Lectureship, University of New Mexico, 1988-1990
  • Award recipient, Institute for Developmental Biology, Tuebingen, Germany
  • Distinguished Speaker, Hilgendorf Lecture, Tuebingen University/Max Planck Institute for Developmental Biology
  • Recipient, Sewall Wright Award, American Society of Naturalists
  • Chancellor’s Distinguished Lecturer and University Medal recipient, Louisiana State University
  • Postdoctoral Teaching Fellowship, University of California at Davis
  • PhD, Oregon State University, 1980
  • MS, Ohio State University, 1976
  • None found