The goal in all this is to come up with (collectively) at least two male-line descendants of each identifiable Sweet "founder," preferably via at least two different sons of the founder. Assuming the DNA test results agree for the documented descendants of the progenitor, we can "reconstruct" the haplotype (DNA pattern) for that progenitor and then compare against the haplotypes of other progenitors to see if they were related. It's really that simple. Consider, for example, the two John Sweets who came to Massachusetts in the early days and both started out in what became Essex County. There is evidence that the one who settled in Newbury spelled his name both Sweet and Swett, but always pronounced it Swett, and it seems likely that many modern Swetts in the US are descended from him. The other one settled in Salem but soon relocated to Rhode Island (or, at least, his family did -- the founder's death is not recorded, and so it's not clear whether he actually moved or not). At any rate, many people have assumed these two were cousins, but nobody has any proof. A DNA study can settle, once and for all, whether the two were indeed related, thereby moving the whole question from the realm of speculation to the realm of fact. (Read on for the answer to this old conundrum.)

Another example is the line of Sweets in Attleborough, Massachusetts. The earliest confirmed ancestor of this line is Henry Sweet, who first appeared in the public record at the time of his marriage in 1687. Although his descendants lived near the Rhode Island Sweets, there is no known connection other than geographic. A DNA study can demonstrate that a family connection does or does not exist. Similarly, there are many other early Sweets in or near Rhode Island who are assumed to belong to the Rhode Island branch, often on the basis of incomplete or circumstantial evidence. Of course, a finding that all such groups share the same Y chromosome would not, by itself, prove that all are descended from the immigrant John Sweet.

Other variants of the name include SWITT, SWEATT, and SWEAT. It remains to be seen how and whether these are related.