(NewsNation) — Same-sex couples are less likely to share the same age, race, ethnicity or other demographic traits with their partners than heterosexuals, data from the Census Bureau shows.

Overall, married couples tend to share similar social backgrounds. Among heterosexual couples, 82% of people had a spouse of the same race. Opposite-sex couples are also more likely to have a spouse who has an age gap of less than two years.

Homosexual couples, on the other hand, are less likely to have spouses of the same age, or race. However, they are more likely to have an income gap of $10,000 or less and to have similar educational levels.

There are also differences between couples made up of two men or two women. Male-male couples were more likely to have bigger age gaps, while female-female couples were more likely to have partners with similar income. When it came to education level, however, both male-male and female-female couples were equally, with slightly more than half of same-sex marriages having partners with similar educational backgrounds.

This is the first study on homogamy among same-sex married couples. A previous study done before same-sex marriage was legalized did compare cohabitating same-sex couples with married heterosexual couples.