A long-term, committed partnership is generally thought to bring out the best in both partners. But new research from the University of Cincinnati found that, regardless of whether the couple is straight, gay or lesbian, long-term cohabitation can also lead to bad habits for partners.

Researchers interviewed 122 people involved in long-term relationships or marriages about their health and lifestyle habits, including smoking, drinking, eating, sleeping and exercising. According to researcher Corinne Reczek, the study found that in straight couples, men were almost always viewed as being the bad influence, whereas in gay and lesbian relationships, participants were more likely to cite both partners as contributing to declining habits.

“The finding that one partner is a ‘direct bad influence’ suggests that individuals converge in health habits across the course of their relationship, because one individual’s unhealthy habits directly promotes the other’s unhealthy habits,” reports Reczek.