If demons are fallen angels then it doesn't make sense that they can reproduce with people.
Jesus replied, âYou are in error because you do not know the Scriptures or the power of God. At the resurrection people will neither marry nor be given in marriage; they will be like the angels in heaven.
Two different species so to speak. No reproduction it seems.
Read it yourself in Hebrew. Most Biblical scholars believe the Hebrew words used to describe the “sons of God” are angels...”fallen angels”. This term is used in other places in the Bible as well.