If you want to go for Ancestry DNA testing then you can do 3 types of basic DNA testing like Mitochondrial, Autosomal and Paternal testing. You can easily predict your ancestry by these DNAs. Paternal or Y-DNA is very helpful where you want
We expect that siblings have common ancestry results but this is not true. In ancestry results, we should know that our parents have different ancestors and involved many generations. It can happen that brothers or sisters have distinct ancestry results.