According to nationally-representative surveys in the United States, hundreds of thousands of straight-identified men have had sex with other men.
from — Why do some straight men have sex with other men? – UBC News. (2024, December 20). UBC News. 

Gay men and other men who have sex with men may be at an increased risk of depression, bipolar disorder and anxiety.
from — Health issues for gay men and other men who have sex with men. (n.d.). Mayo Clinic. 

MSM and gay refer to different things: behaviors and social identities. MSM refers to sexual activities between men, regardless of how they identify, whereas gay can include those activities but is more broadly seen as a cultural identity.
from — Wikipedia contributors. (2025k, May 29). Men who have sex with men. Wikipedia. 

Is an inclusive public health construct used to define the sexual behaviours of males who have sex with other males, regardless of the motivation for engaging in sex or  identification with any or no particular “community”. The words “man” and “sex” are interpreted differently in diverse cultures and societies, as well as by the individuals involved. As a result, the term men who have sex with men covers a large variety of settings and contexts in which male-to-male sex takes place. Perhaps the most important distinction to make is one between men who share a non-heterosexual identity (i.e. gay, homosexual, bisexual or other culture-specific concepts that equate with attraction to other men) and men who view themselves as heterosexual but who engage in sex with other males for various reasons (e.g. isolation, economic compensation, sexual desire, gender scripts) (WHO, UNDP, UNAIDS, MSMGF, 2011).
from — Men who have sex with men | Global Health eLearning Center. (n.d.).