'Offspring' in the Bible

Just as you saw iron mixed with clay, so they will mix themselves with human offspring. Furthermore, they won't remain together, just as iron doesn't mix with clay.

In the first year of Darius the son of Ahasuerus, of Median descent, who was made king over the realm of the Chaldeans—

And when he has become strong, his kingdom will be broken and parted to the four winds of heaven; but not to his offspring, for it will be uprooted; and his kingdom will be for the others and not for these: but not with the same authority as his.

And at [the] end of [some] years they will make an alliance, and the daughter of the king of the south will come to the king of the north to make a peace treaty, but {she will not retain her position of power}, and his offspring will not endure, and she will be given up, she and her attendants and her child supporting her, in those times.