“I rather suspect Science will have managed to open the door to another dimension allowing them in...”
Or...
maybe they are already here and have been all along. Here... procreating and interbreeding... right alongside with humankind.
More than likely you are correct.
Genesis 3:15
And I will put enmity
Between you and the woman,
And between your seed and her Seed;
He shall bruise your head,
And you shall bruise His heel.”
The Devil’s “seed” (Nephilim/Demons/”aliens)....
Some are without any doubt but the floodgates will be opened..I think it could be Demons flood in from another plane..