High arches are a sign of CMT - and thin ankles and lower legs too.... I've had neuros tell me repeatedly early on they suspected inherited/genetic PN due to super high arched thin feet (even though I never had to wear special shoes or anything - but never could get some types of shoes or boots on) and after 9 years and many tests - thet concencous is a form of genetic PN (same as CMT - they think HSANII but there is no genetic test for it yet)... so yes, definately considered a trait.....