So let's lift up our MK's - love them for the unique people they are - encourage them that it's okay to be different, to not know how to answer the question "where are you from" - but also recognize the unique things that make them who they are - allow them to embrace ALL the countries they are from. Share their history with them.
When we dropped Madison off at college, the first few days of orientation were just for the international and missionary kids. When all was said and done, the announcer said to all the kids, "Now...take care...because tomorrow the American's arrive." It was funny, and we all laughed, because we acknowledge the uniqueness that our kids are - that Third Culture Kid - not a kid of one country or another, but unique in their own culture.