I would agree with Mike - the crucial bits are the sourcing and citations for the bits that go together to make up the fact that X is the GG-uncle (or whatever) of Y, not the end result.
That takes me into considering what is necessary to deal with X being the GG-uncle of Y. If it was me, since I believe that a picture is worth a thousand words, I'd include a fragment of a chart showing that relationship near to the text talking about X and Y - I presume that we're talking about some document to contain all this. If I included such a chart, would I think that I needed to document and source the intermediate links between X and Y? No - I think that I'm assuming that there is some reason for skipping over the intermediate generations - such as X being a worthy subject in his own right. If, on the other hand, you're dealing with a controversial ancestry, then the answer is different - but that doesn't sound like your (theoretical) topic.
It's vital to have all this sourced and cited in your database. But what you actually need to print will depend very much on your topic(s) and how much you value clarity and ease of reading.
I'd just throw 2 rules of thumb in - Just because you can, doesn't mean that you should. And... You don't need to provide a citation for the sky being blue (apparently that is a Wikipedia advice topic).
Also - others are highly likely to disagree with me on topics!
