come to think of it, all the ones I can recall had some silkie in them too.. trying to remember if it showed up in polish mixes or not. I really should get to looking for the old pictures of the various projects and mixes and scan them...
As they feather out those tufts aren't obvious any more, just normal small head feathers. What grabs the attention is how naked the head looks especially on large full knobbed birds, looks so much like a balding man with an afro. Front part of the knob is naked, with naked areas reaching out to the sides along the base of knob.
I haven't read anything on that so have to go with totally not professional guesses- both the pea and crest gene affects the skull anatomy- parts get moved around, reduced or expanded etc and the naked neck gene brings that to light...
Partridge is a recessive color, it can pass on undetected until two carrier parents are bred. Almost all silkies that aren't/black blue are partridges.. plus a fair number of blacks are partridge carriers.