I do not know if this is a possibility or you or not, but many of your symptoms sound similar to mine, and I have hereditary neuropathy. Your dad being adopted sent off bells- I am illegitimate, but I know my birth father self medicated with alcohol all his life and my half sister wore leg braces.
My symptoms were limited to clumsiness and walking funny as a kid, but numbness started in my 30's, escalated in my 40's, and went though the roof when I was put on Tricor for off the chart triglycerides. Neurologist stopped that and symptoms retrenched but I walk with a cane, have visible muscle wastage, and take gabapentin and opiates for pain. Life is pretty difficult some days.
The hand weakness comes and goes, based on when the pinched elbow nerves act up . EMG/NCS showed pinched nerves as well as large fiber neuropathy. Skin biopsy showed SFN.
If it is hereditary there is nothing that you can really do, but it would be worth knowing.