Alas, the male-line descendants of Col. Ethan Allwn were very few. Col. Ethan Allen's only son by first wife Mary Brownson was Joseph Allen, who died ae. about 14. Col. Allen had two sons by second wife Frances (Montresor) (Buchanan) Allen -- Ethan Voltaire (later changed to Ethan Alphonso) and Hannibal Montresor. One of these sons, I believe Hannibal, died married but childless in his late 20s. As for Ethan Alphonso Allen's descendants, they struggled on for a few generations -- never more than one or two reproducing males at a time, and equally few females, all with small families, often sickly -- and died out altogether with the last of the surname, Ethan Allen V, in Brooklyn, NY 1911.
I am a descendant of Col. Allen's 2nd wife, Frances (Montresor) (Buchanan) (Allen) Penniman (1760-1834), by her third marriage to [Judge] Jabez Penniman (1764-1841).
See the appendix to Orlin P. Allen, THE ALLEN MEMORIAL (1907), which covers descendants of Samuel Allen of Windsor, Conn., including Col. Ethan Allen. Ethan Allen V (1883-1911), who was married but had no children in 1907, died in 1911, still married, still without children (and no posthumous child, either).
Every Allen family has heard on reliable evidence that they are descended from the hero of Ticonderoga, just as most Adams family in this country knows on equally reliable evidence that they are descended from the Presidents. Many Allens are indeed descended from men named Ethan Allen, because many Revolutionary-era and pioneer parents thought the name was cool, and honored the example. Collectively, these men named Ethan Allen probably contributed a great deal to the history of our country (besides a good deal of confusion to their descendants). They just aren't the well-known one.