John Hewitt

  • Professor Emeritus
  • INSTITUTE FOR BEHAVIORAL GENETICS
  • PSYCHOLOGY & NEUROSCIENCE
Address

Institute for Behavioral Genetics
University of Colorado Boulder
447 UCB
Boulder, CO 80309-0447

Research Interests:

The use of cross-sectional and longitudinal studies of twins and families to study behavioral development, and genetic and environmental influences on behavior, personality, and health. Recent research focus on the development of behavior problems in childhood and adolescence, vulnerability to drug use, abuse, and dependence, genetics and health, and linkage and association studies of behavioral traits. Dr. Hewitt is the Editor-in-Chief of the journal, Behavior Genetics. He was Director of the Institute for Behavioral Genetics from 2001-2022.

Active Grants:

  • R01 DA054087 (mPIs Rhee, Hewitt, Vrieze, Wilson) 05/01/22-02/28/27 Understanding the links between parental and adolescent substance use: complementary natural experiments using the children of twins design. Role: mPI
  • NIDA R01 DA054087 (Rhee (contact PI), Hewitt, Vrieze, Wilson) 5/1/2022 – 4/30/2027. Understanding the links between parental and adolescent substance use: complementary natural experiments using the children of twins design. Role: mPI (till 02-28-23) then co-I

Additional Information:

Current CV

Dr. Hewitt speaks on Human Behavior Genetics: 

Hewitt Former Trainees

Chelsie Benca

Doctoral student

2011-2013

Bo Bishop

Postdoctoral trainee

1998-2001

Angela Brant

Doctoral student

2007-2012

Michael F. Collins

Doctoral trainee

1980-1983

Teresa deCandia

Doctoral student

2009-2012

Sam Dozani

Doctoral student

2014-2017

Lynn Gynther

Doctoral student

1992-1994

Brett Haberstick

Doctoral student 2002-2005

Steve Hallett

Doctoral Trainee

1983-1987

Jeff Lessem

Doctoral student

1993-1999

Rohan Palmer

Doctoral student

2005-2010

Katie Paulich

Doctoral student

2019-2022

Christian Hopfer

K award trainee

1999-2004

Kristin Rasmus

Doctoral student

2014-2016

Chandra Reynolds

Postdoctoral trainee

1994

Soo Rhee

Postdoctoral trainee

1999-2001

K award trainee

2001-2006

Jane Sims

Doctoral Trainee

1984-1988

Elise Eller

Postdoctoral trainee

2001-2002

Naomi Friedman

Postdoctoral trainee

2002-2005

Michael Stallings

Postdoctoral trainee

1993-1994

David Timberlake

Postdoctoral trainee

2003-2006

Tari Topolski

Doctoral student

1993-1997

Tanya Button

Postdoctoral trainee

2005-2006

Carol van Hulle

Doctoral student

1996-2001

Marianne Wamboldt

K award trainee

1997-2002

Steve Wilson

Doctoral student

1993-2002

J Megan Ross

Postdoctoral trainee

2017-2020

Susan Young

K award trainee

2001-2006

Marissa Ehringer

K award trainee

2005-2010

Joe Sakai

K award trainee

2005-2010

Jason Boardman

K award trainee

2005-2010

Matthew Keller

K award trainee

2010-2014

John Hewitt Highlighted Publications

Mental Health, Substance Use, and Related Factors Associated with Recent Use of Cannabis for Sleep: A Co-Twin Control Study

This is a paper in a series of co-twin control studies led by Megan Ross (former IBG postdoc) and her colleagues, using the combined Colorado and Minnesota twin study data (N=3165) on the impact of cannabis legalization (COMN: mPIs Hopfer, Hewitt, Vries, McGue). Observed epidemiological associations between `cannabis use for sleep' and mental health, cognitive function, and tobacco frequency were explained by familial genetic and environmental factors; however, associations remained between using cannabis for sleep and greater problems from cannabis use, greater cannabis frequency, worse sleep quality, and more frequent use of medication and alcohol for sleep. Although direction of causation remains to be determined, co-twin control studies facilitate a focus on potentially causal, rather than merely correlational, associations.

(Behavioral Sleep Medicine, 2025)

Two Decades of Accomplishment and Progress in Behavior Genetics

This is my `exit editorial' reflecting on 23 years as Editor-in-Chief of the journal Behavior Genetics: `Two Decades of Accomplishment and Progress in Behavior Genetics'.

(Behavior Genetics, 2024)