yes any DNA in the past 100 yeas would show up
but many people searching to confirm some family legend
often have troubles - because in their cases - if it did exist - it may have been more than 100 years - and with people who themselves were not even 100% Native American.
Many people who do have Native American ancestry - cant prove it with DNA - because it is too far distant in the past. But Yes - if it is in the past 4 generations - then yes DNA testing should be able to show it. but in many such cases - the people would probably already know such as fact anyway - based on other things - and the DNA test would probably not be anything they didnt already know.
I am "Tagging" this (General) 'Question' of yours, to the 'Group' being "First Nations of North America", in this "Community.FamilySearch" Forum; so that, the members of that group can answer/assist you.
By the way, that 'Group' is a "Public" group, if you wish to join.
@First Nations of North America
DNA testing is one possibility
Yes, I agree! @MarkMcKinney2 MarkMcKinney2 I recommend you get your DNA tested and you will see. I did DNA in 23andMe as well as Ancestry, and the DNA results appear to reflect over 1000 years of ethnic history. My English ethnicity includes residual northwestern Europe because of the Anglo Saxon and Norman invasions. Any Native American ethnicity your gene pool acquired in the past 100 years will definitely show up.