Don't know most of my father's side of the family. Don't know much about anybody beyond my dad's brothers, neither being stable, and contact largely avoided has a result, though I have seen my grandfather and grandmother a number of times.
This was my parents choice and has something to do with my having High Funtioning Autism, stemming from dad's side, and the apparent inherent belief by much of dad's family that such things can be "cured" by a proper southern church.
Never mind that amongst other benifits, I started playing complex piano pieces by age four (without lessons, apparently according to grandma, a sign of "demon possesion". lol), met qualification standards for MENSA when tested in third grade, and can quickly become a walking encyclopedia of anything that draws enough of my interest at any given time. Relevant as I don't really think that these are things that need to be "cured". Sure, the drawback is difficulty in some areas, dealing with people mostly, and some other areas, but the positives outweigh the negatives, and I don't need some nutball relatives messing with my head because of ignorance combined with personal and or mental issues.
Point being, My parents saw to it that I have been kept from certain relatives for what I would agree is a very valid reason, and except for the occassional idle passing thought, when subjects of this sort come up, I have no real interest in changing the situation.