I wonder if the myth could possibly be true- most children reared by animals have great difficulty learning language, walking upright and integrating in any way back into society- much less founding one of the world's greatest civilizations.
Oliver Sacks has written about such children. Most seem to have been reared by dogs, although monkeys come a close second. Sacks talks about a particular "wolf-boy" who was able to learn a language fluently and then describe what it was like to be "pre-linguistic"... there was no such thing as "A Tree", only "The Tree". It is interesting that the capacity for logical thought appears to require the presence of language- of some sort (he includes sign language and algebra).
There is a story attributed to an ancient Egyptian pharoah who decided to find out what the original human language was by raising a few children in complete isolation from birth. It turns out they don't say very much. Unfortunately, these results were not published in the Journal of Negative Results- and the experiment had to be repeated in 1211 AD by a German Emperor. This is analogous to my idea of rearing 2 children in (separated) isolation for 38 years. Following this, they are shown both a Porsche and a Hyundai and asked to say which they feel is the sexier car.