bq. The research — by Matthew A. Holsapple of the University of Michigan and Deborah J. Taub of the University of North Carolina at Greensboro — was based on survey responses of 459 undergraduates at a university in the football bowl subdivision of Division I of the National Collegiate Athletic Association. The participants were given three surveys. One measured their degrees of identification with and support for the football and basketball teams. The other two were survey instruments – previously developed by others and tested for validity — of “modern” sexist and homophobic beliefs…
bq. …In the case of this study, the researchers found a clear, positive association between degree of sports fandom of the college students for their teams, and homophobic and sexist attitudes.
More is here. I haven’t looked for the paper, but there is no way that cheering for college sports teams causes you to become more sexist. Much more likely is that the kind of people who identify strong with college sports teams are more likely to have sexist or homophobic beliefs because of some other (unmeasured?) factor.