Personally, I am pretty flexible but I am hetero. In a poly environment should a group thing occur involving my male companion I wouldn't be opposed to being involved in the scene with them, but I wouldn't be performing sex acts directly involving my male partner. I do believe that a poly family shares its love and I can express an emotional attachment for another man as part of my family. This doesn't disturb my heterosexual sensibilities. In my RL experience I love the man we are romancing almost as much as my girl does ... but she is the only one of the two of us who wants to "do" him.