There are variations in this text from extant Hebrew versions beyond the scope of this discussion, but translators to Greek had to decide when to use the term "genea" and how. Maybe there is a clue there.
Sulla,
You are right that this does not warrant much more discussion. Neither of us buy the notion. It's a foreign idea I started to explore never having been a JW and see it only as a strange calamity that fell on my household. And as you said, you have already argued over this with a thousand others. However, ...
If Matthew was aware of when Jerusalem fell to the Babylonians, then there was an implicit notion of what 14 generations spread over nearly 600 years implies for the length of a generation. I can't say if he knew that was six centuries ago, but it possible. I suspect Josephus did. But the successive WT definitions employed over the past century now violate all common sense. Rationalizing them is leaning over backwards.
What was the resemblance?
What made Rome different from the Persians who ruled Judea for a couple hundred years? Or what made Rome different from the Seleucid rulers two centuries earlier that violated the temple as described in Maccabees I & II? They destroyed the Temple and sent the population off into slavery. The trouble was, Peter had already passed away as far as anyone knows. It's an anachronism in the text. The NWT appendix claims these epistles were written from Babylon - which the elder and overseer that visited my house on Saturdays a couple years ago kept claiming had been destroyed already forever. A writer's retreat?
As to the other matters: the Septuagint or comparing the other synoptic gospels, that's simply what you do if you run an investigation. If this were archeology we would be sifting through sand with trowels rather than excavators. Patterns do emerge. In one gospel, Christ speaks of the "kingdom of heaven'; in another it's "my father's kingdom". On the cross to the good thief, it was "paradise" he would enter with him that day.
Talking to people of other faiths, like the one in which I grew up, for some the notion is that Christ's words are meant to throw people off balance; that the Gospels are meant to stir things up, to make people think twice or find in them something the reader hadn't seen before at age twelve, twenty or forty-five. ...I've even heard people say that of Tol'stoy too,contemporary of Russell and Rutherford in some ways, but he made a better writer than a cult founder... But the odd situation we have here is that we are debating a pretended static presentation of the Scriptures in their entirety ( inerrant, predictive of the future, explained and enforced by the authority) which gets revised even as we watch.
With regard to that process of establishing authority via witnessing invisible events, I've been thinking about another topic...