Short answer to this is, there are usually memories to support this theory. Furthermore, if you have a lesbian alter you either have been abuse by the same sex and have suppress those feelings and use them in other ways throughout your life. Now in discovery its your choice or the alter to decide if you want a lesbian relationship or not. Same with gay male alter usually there are memories to support that even if only friendly towards them. Now with discovery it depends on what you decide your gay male's role will be in your life.