Saw a neurologist, showing clear signs of hnpp, but parents never showed signs. need insurance for testing,but is probability low for being positive?

HNPP: Hereditary neuropathy with sensitivity to pressure palsy is of variable penetrance and can be so mild in a parent that it is missed, or you may be a new mutation. Apart from your perhaps having an entitlement to special shoes, there's really no treatment and hence it's not always worth doing confirmatory genetic testing, such as exists anyway. You don't want a nerve biopsy. Best wishes.