I typed this on my phone. Please forgive the typos.
Hi and welcome,
The possibility of misdiagnosis is more likely to depend on the totality of your diagnostic evidence, 'neuropathy' is the term used to describe problems with the nerves, usually the 'peripheral nervous system' and not the 'central nervous system' and because MS is a condition that affects the CNS a lot of MS symptoms are also found in many other conditions too.
Neuropathy is associated with many different types of underlying medical conditions eg structural spinal issues, vit deficiency, alcoholism, diabetes, shingles etc etc. so if you have a dx of an associated condition then it's more likely that the neuropathy is from that, although neuropathy can be hard to work out the causation. You probably should keep in mind that 'Lexapro' has been associated many side effects including neuropathy so it's 'possible' the neuropathy is medication related and whilst thinking of medication related side effects....
...the more common side effects of Gabapentin is dizziness, fatigue and various mental health issues so if things have developed since taking the medication for neuropathy there is the 'possibility' that it's side effect related.
In regards to MS running in families, MS is not like a genetically inheritable condition, so whilst you can find multiple family members with MS, it's actually rare and more common to be the only person with MS in the family even if you're an identical twin.
Hope that helps........JJ