My sister, my only sibling and I have literally no physical traits in common. Whatever trait I inherited from one parent she inherited from the other. We're thinking of using one of those genome analysis services to learn information about our mysterious geographical ancestral origins.
We're wondering if, despite our differences in appearance, if only one of us submitted our genome for analysis, the geographic origin results would still be accurate for the other. Because our parents may both have diverse lineages, the answer might not be so cut and dried.
Understand, please, that we are not so much looking to find out the general "where" of our origins as we are to have each of us know what our individual genetic heritage is.