Does anyone else do this?

Moving your hand as you sing phrases is a natural musical gesture - it probably stems from your desire to be accurate, since these eurhythmic gestures ( yes, it's a real word - not just the name of an old band) are helpful to many people. As far as copying vocalsounds - that too is often done without realizing it. I am originally from Boston, and have lived in NY for many years - and now have far less of the "pahk the cah ovuh heah!" accent I used to have - but one Ben Affleck/Boston movie, and it starts to creep back for a little while - I say things like "umbreller" and "bananner" - and almost think of rooting for the Red Sox again - but that is not allowed in this house.

People often comment that no-English native speakers, when they sing American-style pop music, have NO ACCENT. That is because they learned that style of singing by - listening to American groups! Mila Kunis has NO ACCENT - she learned all her English from American TV! It is just human nature. Unless you do what you do to the point where people tell you that it is affected - stop worrying. And keep singing! (I taught voice and choral music for over 30 years - EVERYONE should sing, and sing out like it comes from your heart!)

Happy Holidays, 'Liz. Good to see you out here again.

You sound like you really enjoy it all, which is delightful. It could be worse. As an old stoner guitarist, I might do a little "air guitar" to a really good solo. The heart and soul are where it all ends up.

Gravity, indeed.

https://www.youtube.com/watch?v=Fo4746XZgw8

You definitely aren't alone. I almost can't sing unless I'm holding a guitar or bass, it just feels so wrong not to have something to do with my hands.