You seem to be implying that promotion of one's genes is the only worthwhile goal. Stipulating that value system for the sake of argument, procreation is hardly the only way to do that. Literally anything you do in life affects other life forms which share some of your genes.
"Summary:
Male homosexuality doesn't make complete sense from an evolutionary point of view. One possible explanation is what evolutionary psychologists call the "kin selection hypothesis." What that means is that homosexuality may convey an indirect benefit by enhancing the survival prospects of close relatives."