Genesis 6:1

1 And Noe was five hundred years old, and he begot three sons, Sem, Cham, and Japheth. And it came to pass when men began to be numerous upon the earth, and daughters were born to them,

Genesis 6:1 Meaning and Commentary

Genesis 6:1

And it came to pass, when men began to multiply upon the
face of the earth
Either mankind in general, or rather the posterity of Cain, who were mere natural men, such as they were when born into the world, and as brought up in it, destitute of the grace of God, and of the knowledge and fear of him; and who in proportion much more multiplied than the posterity of Seth, because of the practice of polygamy, which by the example of Lamech, one of that race, might prevail among them: and daughters were born unto them;
not daughters only, but sons also, though it may be more daughters than sons, or it may denote remarkable ones, for their beauty or immodesty, or both; and chiefly this is observed for the sake of what follows.

Genesis 6:1 In-Context

1 And Noe was five hundred years old, and he begot three sons, Sem, Cham, and Japheth. And it came to pass when men began to be numerous upon the earth, and daughters were born to them,
2 that the sons of God having seen the daughters of men that they were beautiful, took to themselves wives of all whom they chose.
3 And the Lord God said, My Spirit shall certainly not remain among these men for ever, because they are flesh, but their days shall be an hundred and twenty years.
4 Now the giants were upon the earth in those days; and after that when the sons of God were wont to go in to the daughters of men, they bore to them, those were the giants of old, the men of renown.
5 And the Lord God, having seen that the wicked actions of men were multiplied upon the earth, and that every one in his heart was intently brooding over evil continually,

Footnotes 1

The Brenton translation of the Septuagint is in the public domain.