Some scholars have argued that the Nephilim are simply wicked men like Cain, but worse, nothing more. They base their argument on the statement of “and also afterward” in verse 4, as they say, the Nephilim “were on the earth in those days, and also afterward, when the sons of God came into the daughters of man and they bore children to them.” In other words, the Nephilim were on the earth before the “sons of God had relations with “the daughters of man.”
This position does not outweigh the correct interpretation that the “sons of God”, who were rebel angels, took on human form, had relations with the “daughters of man,” and produced a mighty offspring of half-man, half-angelic. There are some translations, which have moved the phrase “and also afterward” closer to the beginning of verse 4, which would identify the Nephilim with the “mighty men.” For example: “In those days, as well as afterward, there were giants [Heb., hannephilim] on the earth, who were born to the sons of the gods whenever they had intercourse with the daughters of men; these were the heroes [Heb., haggibborim] who were men of note in days of old.”―Genesis 6:4, AT, NIV, and TEV.
The Greek Septuagint, a Greek translation of the Hebrew Old Testament made between 280 and 150 B.C.E., also agrees that both the “Nephilim” and “mighty men” are one and the same, using the word gigantes (giants) to translate both expressions. If we look at the context, we will see that in verses 1 through 3, the “sons of God” were taking wives for themselves and that God had tired of this rebellious behavior and said of man, “his days shall be 120 years.” Thus, in verse 4, we see that the Nephilim was in the earth “in those days.” “In those days” was obvious referring to when God made the statement. Therefore, it showed that this ongoing situation continued, “also afterward, when the sons of God came into the daughters of man and they bore children to them.”