Hi Nancy,
The DNA test your nephew took may have been "autosomal" which tests DNA from both parents, not the Y test, which tests exclusively the paternal line. The Y test is used for surname research, and would not yield Norse and Germanic origins as you mention, because the Y locates the particular haplogroup which is passed down only by males to male offspring. My autosomal test also yielded norse and germanic origins, but it is the Y chromosome which yields the origins of the paternal lineage. Y DNA testing goes back thousands of years, even tens of thousands, while the autosomal test goes back 5 generations or so, and indicates more recent origins (thus your reference both to Norse and Germanic, which shows a mixing or autosomal result, rather than the purely male chromosome Y-DNA test I was referring to). A Y-DNA test would not indicate Norse or Germanic origin. A Y test would indicate the course of tens of thousands of years of migration of a particular male group of ancestors, such as an R or I haplogroup.
Paternal lineage does not necessarily mean that everyone with the same surname has the same origin. Some unrelated people share the same surname, and some related people share an unrelated surname. For the Romany people, names were adopted from the host country and so there are Kennedys who share a Romany Y-DNA which originated in India (H1a1a haplogroup), and also Kennedys whose Y DNA is associated with the R haplogroup which is prevalent in Europe, but which originated in central asia in the steppes.
The reason that I decided to do my own Y DNA test was because I had researched the Renison name extensively, coming to the conclusion that it was not Irish, that it was possibly Norse, and prior to the name going to Ireland, it had been used in England. But I could not get very far back with Renison or Rennison - meaning, I could not get past about the 1600s. The Dictionary of Surnames in England says:
"Rennison, Renison - (1) Bapt. 'the son of Reynold,' a corruption of Reynoldson (2) Bapt. 'the son of Reyner' (v. Rayner), a corruption of Reynerson. No doubt both (1) and (2) have contributed. But as Reyner was a great Yorkshire font name in the 13th and 14th centuries, (2) must be looked upon as the chief parent.
When researching Reyner (also spelled Rayner), it shows the name is of early medieval English origin, deriving from the Old Norman French male given name Rainer or Reiner, itself coming from the old German Raginhari. The name was introduced into England by the Normans, who were of course Norse, after 1066. There are also references to the name "Rennie" which is a scottish name appearing as far back as the 1500s.
After 1066, the Normans introduced surnames into England, starting with the nobles, and slowly spreading to the rest of the populace. The first recorded use of Rayner was from 1216. The fact that Renison does not appear very early in the history, and only begins to appear in the 1600s and 1700s in Britain, Scotland and Ireland, does not convince me that it is a name of very early derivation. Instead, it may have developed after 1500 when the Romanies began to enter Britain in around 1506.
What is undeniable, however, is that our particular Renison family from Ireland traces patrilineal lines back to India when that group left India in approximately 1,000 A.D. Because Y-DNA does not recombine with the mother's DNA, but is passed rather unchanged from father to son (only mutating slightly every few generations), tracing the paternal lineage to others who share the same Y-DNA signature is a matter of science. The Y-DNA test that I performed along with my fourth cousin in South Africa differed only in one marker out of 37 markers, showing an almost exact match, and confirming our relationship not only to eachother, but to the population of Indians to departed India a thousand years ago. Whether that marker is contained in the Y-DNA of all Renisons, or only some of them, or just our small branch of the family remains to be seen because I have not seen any other Renisons who appear on the Y-DNA testing site ysearch.org. It is most likely that other Renisons have only done the autosomal test, and that would probably show nothing of interest in the surname research area.