Using genetics it is hoped that siblings can locate each other or
The mtDNA test is for finding your maternal line ancestry. Both males and females can be tested since you get your mtDNA from your mother. Only females pass their mtDNA on to their children.
The Autosomal or Family Finder test is for finding your both maternal and paternal ancestry. Both males and females can be tested and FamilyTreeDNA guarantees finding others that have tested back to 5 to 6 generations.
If you are stuck at a brick wall or dealing with an adoption with your research, DNA testing matches will connect you to others family members you can share research with to find your common ancestor. Finding a genetic match will help you to focus your research on families you have a connection to, instead of researching all the families with the same name in the same area. This saves time and makes researching materials from efficient.