Once again, sin had NOTHING to do with creating giants.
Actually it did
This happened:
וַיִּרְא֤וּ בְנֵי־הָֽאֱלֹהִים֙ אֶת־בְּנ֣וֹת הָֽאָדָ֔ם כִּ֥י טֹבֹ֖ת הֵ֑נָּה וַיִּקְח֤וּ לָהֶם֙ נָשִׁ֔ים מִכֹּ֖ל אֲשֶׁ֥ר בָּחָֽרוּ׃
the [males among the]
divine beings saw how pleasing the human women were and took wives from among those who delighted them.—
הַנְּפִלִ֞ים הָי֣וּ בָאָ֘רֶץ֮ בַּיָּמִ֣ים הָהֵם֒ וְגַ֣ם אַֽחֲרֵי־כֵ֗ן אֲשֶׁ֨ר יָבֹ֜אוּ בְּנֵ֤י הָֽאֱלֹהִים֙ אֶל־בְּנ֣וֹת הָֽאָדָ֔ם וְיָלְד֖וּ לָהֶ֑ם הֵ֧מָּה הַגִּבֹּרִ֛ים אֲשֶׁ֥ר מֵעוֹלָ֖ם אַנְשֵׁ֥י הַשֵּֽׁם׃ {פ}
It was then, and later too, that the Nephilim appeared on earth—
when divine beings cohabited with the human women, who bore them offspring. Such were the heroes of old, the men of renown.
6 And the angels—who did not keep their own position of authority but deserted their proper place—He has kept in everlasting shackles under gloomy darkness until the judgment of the great Day.
7
In the same way as these angels, Sodom and Gomorrah and the cities around them—
having given themselves over to sexual immorality and gone after a different sort of flesh—are displayed as an example, suffering the punishment of eternal fire