My brother passed away when he was 24, in 1999.
My mother knows about all of my twitching and freaking out, since it started happening, and she recently read an article I sent to her about how twitching can seem like having worms under the skin.
This prompted a memory of her with my brother. He had just gotten done working out, then he plopped down on the couch to rest. My mom noticed his muscles were jumping around on his arms and legs. She said, "OMG, what is that? Do you have worms under your skin or something?" and my brother just looked at his body, shrugged his shoulders and said, "I don't know. It just does that."
We had a great laugh about this, because that is how different he and I were. He would not have been phased by his twitching, whereas me over here, well, that's not the case.
We are not sure if he had twitching all the time though, or if it was just after he worked out. Probably just after his work-outs.