A useful way to proceed would be to develop heirarchies, in which behaviors would be grouped by the level of subjectivity involved in understanding them. We could all agree that suicide and depression are harmful, for example. These would be Level One diagnoses. We would move on down from there, clearly acknowledging the amount of subjectivity involved in each grouping. In all those higher categories, it would be clear there had been that final arbitrary jump of subjective judgment.
Most people form their opinions from the social group they're in.
There's strong anti-gay feeling in some social subgroups, whereas on the other hand, liberals almost automatically assume the condition is healthy. Of course, people don't have time to study every issue. Even in studying those issues, most people aren't aware that the facts they do have before them may be distorted. This is true in the debate over money for AIDS research. Of course, if someone has a loved one dying of AIDS, no help is ever enough.