Using a Public Policy Polling poll on food issues and Pew data on gay marriage opinions, Dave Gilson of Mother Jones found that the people who won't try sushi are, age-wise at least, the same people who don't approve of gay marriage.
On a basic level it makes sense: younger people are more open-minded and therefore willing to both support ideas of family that aren't necessarily traditional and try raw fish. Trying sushi and supporting gay marriage are also related in other ways: Public Policy Polling found that many more Democrats would try sushi than Republicans; the same goes for supporting gay marriage. And like millennials, both sushi and the issue of marriage equality came of age in the 90s: Food & Wine pointed out that "the number of sushi bars in the U.S. quintupled between 1988 and 1998." Gay marriage became a national issue in 1993 after a Hawaii court case.