I'm similar to the OP. I can see all viewpoints and have no intrinsic "self" viewpoint. I think the ability comes from trying to "fit in" when I was younger and realizing that every group/person has a different viewpoint and to "fit in" I'd just assume the viewpoint of the person/group I was involved with at the time. It has it's advantages-- if I don't like someone I can play one hell of a devil's advocate, or if I meet a new person from a completely different race/culture/background I can subconsciously absorb their viewpoint as they talk.
It manifests in other ways too-- such as I don't have a moral center because I have no main philosophy I live by. I pick and choose the best morals for the given situation because I think every situation needs to be handled in it's own unique way, not by a single dogma. The only moral I'd say I have is: what's in the best interest of the whole, meaning not what benefits me exclusively or my friends or my family or my country, but what benefits the majority of humanity even if it means I have to make sacrifices.
The downside though is that I won't constantly agree with friends/family on issues because I see a bigger picture outside their wants. I've also been told I'm not "trustworthy" because I change my "opinion" too much. I view philosophy/culture/morals as tools and not every job requires the same tools. This is why I can't be religious, I can't follow a single dogma for every situation, not when there's a better dogma for a given situation out there.