Linguistic cladistics? Based on vocabulary? Linguistic froth, such as loan words from other languages, frequently becomes a source of heated debate. The deep structures of language that can provide a relatively stable field for analysis are more subtle. These include verb-substantive-object order, verbs of giving or receiving, noun declensions, and the like. But even these are subject to extreme transformations. Besides, any genetic tree that places English more than one node away from Frisian is too arbitrary to be credible.
David C. Oshel
Cedar Rapids, Iowa