(Potentially NSFW) Why do I do such strange things in my sleep?

I have always done very bizarre things while I’m sleeping. I am always slightly conscious that I’m doing it, but I am not awake enough to stop myself.
I used to spit in my sleep. Not drool, but literally roll over and spit. (Sorry, that’s gross, I know.) Usually I was dreaming about having something foul in my mouth, or brushing my teeth.
Now, lately, it has been undressing myself in my sleep. I can’t remember what I’m dreaming about most of the time.. but I am somewhat conscious that I’m doing it. Every night.

Is this related somehow to sleep walking? I have never been one to sleep walk, not since I was a toddler anyhow. My sister sleepwalks, though. Could it be a hereditary thing?

Do you do weird things in your sleep?