What is Relatedness?

[JoatSimeon at aol.com]

>X99Lynx at aol.com writes:

>What if five lexical attributes appear as shared innovations between IE
>languages A and B and therefore evidence a greater relatedness between the two
>than a language C - which has none of them.  What if however Language C shares
>a totally valid morphological innovation with B not found in Language A?

-- these are known as isogloss boundaries, and present no fundamental problems.