It is possible for a predominately heterosexual male to develop homosexual feelings. Often, this happens because there is a lack of platonic friendship in common with other male peers. How much friendship and acceptance one needs depends on each particular person.
I have always been the type to need one or two very close male friends in my life who I see as almost “brothers.” They are the ones who enable me to develop my gender identity. Some other guys may find acceptance and identity through sports teams/hobby groups or other large organizations (as I did at various points in my life). I have found that a cause of the heterosexual preference is acceptance from people in the same gender and assimilation to that group at critical stages of psychological-sexual development.
These “critical stages” normally occur before puberty but can be influenced quite a bit during and after adolescence. Everyone has a different level of acceptance and assimilation to that needs to be reached with same-gender friends. Some need a little some need a lot. Some may never find enough acceptance to satisfy them. It all depends on the individual. I have yet to meet one male that did not need some form of acceptance from his gender. Same gender friends do serve some purpose and fulfill some kind of need, otherwise heterosexual males wouldn’t have male friends at all.
I suppose it is possible to make up for “lost time” by acquiring new same-gender friends but I think that this also would depend on the individual’s needs. When I was deprived of male friends due to change in schools or location, I noticed some homosexual feelings getting more frequent (in my case, thinking about mutual masturbation more often). I also felt arousal and anxiety around other attractive guys during these times. These feelings were not only more frequent but I worried about them more than when I had a platonic social network of other guys. Then, when I made some close male friends and spent time with them often, these feelings seemed to subside quite a bit. They seemed to go away naturally yet they never entirely disappeared forever.
I must take a moment to point out that homosexual feelings do not necessarily lead to homosexual actions. Often they don’t. The majority of people have had a fantasy about the same sex at some point in their life but few act out on these feelings regularly.
When I was lonely and deprived again for a period of months or years, they came back strong. I can’t can’t say that all homosexuality comes from lack of supportive and accepting male friends. Homosexuality is not entirely caused because a guy didn’t have enough male friends. But I can say that heterosexuals may acquire homosexual feelings for this reason. It’s also safe to say that some homosexuals end up with a homosexual preference due to the cause listed above. Unfortunately, other genetic and environmental issues play a part in everyone’s sexuality. It’s difficult to say how much of which cause is enough to create a homosexual or heterosexual lifestyle. However, we can say that, at the very least that the three factors of: genetics, environment, and peer acceptance definitely play a role in sexuality development overall. There may be more influential factors still undiscovered or yet to be fully proven.
I was surprised to find out that this is not the only source that speaks about this phenomenon. The following article, found on the Internet, mentions the same idea of the need for a “same-sex-acceptance”: