Wiggly legs

Factual Questions
#1

I’ve never really asked anyone about this, so I don’t know if this is perfectly normal, though I suspect it probably happens to a lot of people. See, if I’m sitting down, and put my weight on the ball of my foot, and sorta half-way tense up my ankle, my leg starts vibrating. My knee moves up and down a half inch or so, and faster than I could consciously manage. If I let it start, it’ll happen autonomously.

I particularly remember this from childhood, sitting in a desk at school. My father has exactly the same experience, and he also did it particularly often in childhood. Do everyone’s legs do this? Or only some people’s? Or are we just freaks?

Incidentally, I have mild restless legs, and so does my father. I wonder whether those things are related.

#2

I’ve had this exact condition since injuring my lower spine (shattered disk) about 36 years ago. It’s a little less common these days than originally.

#3

I’ve always had that. It never interfered with anything so I just assumed it was harmless.

#4

I do that purposely. It helps me concentrate.

#5

My legs do that, and other wiggly stuff all the time. It even happens when I stand on them, which makes me sway, I have been told it is restless leg syndrome, but it does not bug me and I kind of like it.