Is there a gap in cultural ethics between members of minority groups and non-members of minority groups?

I'm not exactly sure which discussions or Y!A users you are referring to, but I like to think of myself as an equality-first type of person. I don't, for example, think the mom should always get custody in divorce cases, and I think alimony should be abolished all together. People do tend toward self-interest, though, and it seems much more common for people to support causes that directly affect them. But perhaps people do what you describe and support what you perceive as an inequality on one side, because they feel like they are still disadvantaged by the situation, or that the inequality is on the other side. Perception can be a stronger motivator than fact.