Minnesota Center for Twin and Family Research: Tracking Psychological Development for 35 Years

In 1987, Dr. Matt McGue, professor of the UMN Department of Psychology, along with his colleagues, set out to explore the possibility that there might be a genetic component in the development of substance dependence. Does it come from being exposed to substances from people they know or from places and situations in which they find themselves?

After McGue and his colleagues, David Lykken and William Iacono, secured a grant from the National Institute of Drug Abuse (NIDA) for their study, the next question became: How does one study this ever-trending, widely debated topic of “nature vs. nurture” in science? 

Twins. 

The grant laid the groundwork for what is now the Minnesota Center for Twin and Family Research (MCTFR). Starting with 666 (which is “an odd number,” McGue recognizes) pairs of male twins for this initial drug abuse study, the center has since grown to include over 10,000 twins and their parents over the last 35 years. 

Starting the First Twin Cohort

The University of Minnesota’s psychology department has long had an interest in the genetics of behavior, going back almost 100 years. Scholars at the University had already done some preliminary research on the inheritance of alcoholism and were therefore a group particularly suited to receive the NIDA grant. 

“We had that tradition. We had training,” says McGue. 

The State of Minnesota also had twin registries, something not common among states back then. Emeritus Professor David Lykken (1928 - 2006) had established a system to identify twins in the state, giving the grant recipients another leg up.

The principal investigators involved in the study started with twins who were either 11 or 17 years old. The rationale behind the ages was that 11-year-olds typically don’t have experience with drugs, and 17-year-olds are at an age just before a peak period of exposure. 

“The challenge was we had a rather ambitious assessment,” claims McGue. Many of the families coming for the study lived as far as 250 or more miles away from the metro area, and the survey assessments were not speedy. Most did not want to stay more than a day, even if lodgings were provided. “We needed to balance what we wanted to do scientifically, in terms of assessing families, with their time.”

This challenge led to a redesign of the study—families would come for eight hours a day, every three years, and that’s how a massive longitudinal dataset was created. Now, of course, other modalities like online surveys, Zoom, and phone calls have made it even easier for participants. 

What’s remarkable is that these twins, who first joined the study around 1990, are still being followed.

“Those studies, those assessments, are done, but there are other, more specialized research questions being asked. There are still people following them up right now,” says McGue.

The Expansion of MCTFR

Twin-study research is expensive, and although the center wanted to study both male and female twins from the get-go, money was the bottleneck. 

“As soon as we got an opportunity and knew what we were doing, we put in a grant to study female twins, but not at NIDA, at the National Institute of Alcohol Abuse and Alcoholism (NIAAA). And so the first expansion of the study was to balance the gender of the sample,” explains McGue.

The second big expansion was the start of the Sibling Interaction and Behavior Study (SIBS), which is a study of adoptive and biological siblings and their parents. 

“What we wanted to do is get a better handle on the environmental factors, and the best way to do that, I think, still today, is to study families where the relatives or the individuals in the family are not genetically related.”

A unique aspect of these studies is how they get data from twins, siblings, and parents. Interestingly, there is not a lot of research work in psychology that has this family perspective. “In our case, we got almost 100% of the moms, and I would say maybe close to 90% of the dads to participate,” says McGue. 

Since then, the growth of MCTFR has been astonishing. It now has six externally funded research grants, 26 full-time research staff, six principal investigators, 12 graduate student researchers, and 12 undergraduate research assistants.

The center is at a major inflection point. Beginning in 2020, a new cohort of twins began enrolling in the infant twin registry, so researchers now have participants ranging from four months to their mid-80s. 

“Now that we have participants whose ages span decades, from infants to seniors, it provides us with a strong foundation to conduct genetically-informed research across the lifespan,” says Neely Miller, current director of the MCTFR. 

Need for Better Data Infrastructure 

While the center’s original mission has largely remained the same–understanding the influence of both genetics and the environment in the development of certain health outcomes—some changes have been necessary with the center’s increase in scale and scope.

The center aims to restructure its data storage by digitizing paper records and combining them with existing digital data in one central system, making it easier for researchers to find and use the center's data and documentation.

One challenge was the storage and usability of the collected data, which now numbers in the millions of data points. When McGue and his colleagues started in the early ‘90s, data were collected using pen and paper. As the world began to shift to digital data collection, thousands of banker boxes full of paper were digitized and then recycled. 

The problem now was that different kinds of data were housed in various storage solutions. This not only made it difficult to integrate different types of data, but there was also no comprehensive system for tracking metadata across various domains.

Researchers from different institutes frequently request MCTFR’s datasets, which requires extensive manual labor to curate—work that depends on the expertise of someone familiar with the data structure.

To modernize the data infrastructure, the MCTFR applied for and received a grant from the University of Minnesota’s Research and Innovation Office (RIO) Research Infrastructure Investment Program in 2024. 

“Our initial goal with the infrastructure grant is to centralize all metadata and documentation so that they can be ingested into the database. The next step will be to refactor our data documentation so that ​​when a researcher extracts data from our database, they can also obtain a list of index terms and documentation,” says Miller. 

The plan is to eventually create a collection of curated data sets for researchers and establish a user-friendly data extraction and sharing system. They are over halfway through the metadata documentation process.

Keeping the MCTFR Running 

When asked what keeps such a large institution like the MCTFR running, both Miller and McGue unanimously agree it’s the people, both the families participating and the staff conducting the studies. 

“We are really lucky that we have a cadre of incredibly dedicated staff, some of whom have been with us for 30 years, since the very beginning of MCTFR,” says Miller. “It's also remarkable that our families have continued to participate in our assessments, now spanning multiple generations."

Students also play a big role. Back in the ‘90s, undergrads would go to the Minnesota Department of Health and leaf through the books, identifying twin birth records, photocopying them, and then tracking the families down. A lot of the administrative work is still done by undergrads to this day, while graduate students often do their dissertations with the center.

“[The undergraduates] are very talented. They're young, so they don't have a lot of experience, but they're very smart and motivated. And we train them. It might take six months to train somebody, but they're here for a couple of years,” says McGue.

The Lasting Legacy 

For McGue, it’s being able to study lives through time that is the extraordinary aspect of the work being done at the MCTFR. Nearly 900 publications have come from the center, all of which were instrumental in understanding the consequences of drug abuse, mental disorders, mental health, cognition, and so much more. 

The MCTFR is dedicated to increasing the accessibility of the unique data they have collected so that its work can continue to generate new knowledge.

“Ultimately, what I hope is that the individuals and the families who participate in our projects have had a positive experience, and understand the impact that they've had on all of these discoveries,” says Miller.