And I tend to veer into another angle... It seems possible to me that they are among us all the time and have been for generations, whether occasionally invisible or with some kind of mind control over us making us only rarely see them.

lol That sounds goofy to me- in other words, I just don't know. On the other hand, positing that they are from another world seems a bit of a leap to me. As I said, I tend to think that they are much closer to us than that.