After spending all these years in school (over 25) I'm truly wondering what anyone really checks on.
Examples:
* Nobody has ever asked for my marriage certificate at a university to prove that I am married.
* Nobody has ever asked for my DD-214 at a university to prove that I am a veteran. (the VA asked for it though.)
* Nobody has ever asked for my birth certificate or passport at a univeristy to prove that I am a citizen. I presented an International Immunization Record at this last U and it didn't cause them pause to ask "where are you from"?
* Nobody has ever asked for an audited financial statement (other than self-reported) to prove my financial position (except that I have provided tax returns for "verification")
* Nobody has ever asked for DNA (or any other evidence) at a university to prove my ethnicity.
* I've never had to prove my residency to a University short of self-reporting. Proving my residency to Equifax (to correct thier error) was a major PITA.
* When my wife and I got married in March 2000 in the NC mountains, she was asked her ethnicity on the the marriage licence application. She replied "Native American, Cherokee" - her self-reporting was the extent of any verification.
* We have at this U unfavorable parking for freshman students -- a young friend, when asked while getting his parking permit, simply claimed to be a sophomore. Nobody checked.
I'm not advocating that people lie -- but it would appear to me that self-reporting an error is an easy process in our university system.
In this century, in this country, ethnicity is not defined by law. It used to be -- that was bad by most people's standards.
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As for using OxfordAncestors or AncestryDNA and the like to determine ethnicity, one must remember that our ancestry is not as simple as that in most cases. Doing a check on Y-DNA or mtDNA will only return results for one lineal branch of our family tree. It's possible for that result to be very different than our self-reported ethnicity or even our phenotypic ethnicity.
Having students complete a four or five generation ancestry chart would offer more information about the student's ancestry -- but that doesn't establish ethnicity either. It can make the student more aware of where he came from though, not a bad thing.
At the 5th generation beyond the student there are:
1 student
2 parents
4 grandparents
8 great-grandparents
16 great-great grandparents
===
30 contributors to that student's "ancestry"
add just two more generations and:
32 3rd great grandparents
64 4th great grandparents
===
126 contributors to that student's ancestry
If we assume birth of child at 21 years old (an assumption capable of wide variation) for a child born in 1990, we have:
1990 child
1970 parents
1950 grandparents
1930 great-grandparents
1910 great-great grandparents
1890 3rd great grandparents
1870 4th great grandparents
Six generations at 100 years. An awful lot of history in there to look at...

In my family, 4 generations made 100 years.
If you subscribe to the old "one drop rule" -- at 6 generations beyond ourself, most of us can claim to be 1/126 "anything we want".