Matthew 22:23-33 ESV
[23] The same day Sadducees came to him, who say that there is no resurrection, and they asked him a question, [24] saying, “Teacher, Moses said, ‘If a man dies having no children, his brother must marry the widow and raise up offspring for his brother.’ [25] Now there were seven brothers among us. The first married and died, and having no offspring left his wife to his brother. [26] So too the second and third, down to the seventh. [27] After them all, the woman died. [28] In the resurrection, therefore, of the seven, whose wife will she be? For they all had her.” [29] But Jesus answered them, “You are wrong, because you know neither the Scriptures nor the power of God. [30]
For in the resurrection they neither marry nor are given in marriage, but are like angels in heaven. [31] And as for the resurrection of the dead, have you not read what was said to you by God: [32] ‘I am the God of Abraham, and the God of Isaac, and the God of Jacob’? He is not God of the dead, but of the living.” [33] And when the crowd heard it, they were astonished at his teaching.
When we actually look at this passage, Jesus never says that angels cannot mate with women, only that they do not do so in an edenic afterlife following the resurrection.
As the scriptures say, they are like angels in heaven.
And yet here, in Genesis 6, we are not speaking of events in heaven, but rather events on earth. And we aren't speaking of what angels do in God's kingdom. Rather we are talking about rebellious angels.
2 Peter 2:4-6 ESV
[4] For if God did not spare angels when they sinned, but cast them into hell and committed them to chains of gloomy darkness to be kept until the judgment; [5] if he did not spare the ancient world, but preserved Noah, a herald of righteousness, with seven others, when he brought a flood upon the world of the ungodly;
As Peter notes, God did not spare them, but cast them into hell for their transgressions. But Noah was preserved.
Jude 1:6-7 ESV
[6] And the angels who did not stay within their own position of authority, but left their proper dwelling, he has kept in eternal chains under gloomy darkness until the judgment of the great day— [7] just as Sodom and Gomorrah and the surrounding cities, which likewise indulged in sexual immorality and pursued unnatural desire, serve as an example by undergoing a punishment of eternal fire.
For the left their proper dwelling, and just as sodom and Gomorrah and the surrounding cities, these angels indulged in sexual immorality and pursued unnatural desire.
In fact, in the book of Genesis, angels do many human-like things. Jacob wrestled the angel of God, Genesis 32:24.
In Genesis 18:1-8 angels ate a meal together with Abraham.
In the story of Wisdom and Gomorrah, people want to mate with angels before they turn and destroy the city.
Genesis 19:4-5 NIV
[4] Before they had gone to bed, all the men from every part of the city of Sodom—both young and old—surrounded the house. [5] They called to Lot, “Where are the men who came to you tonight? Bring them out to us so that we can have sex with them.”
Genesis 19:10, the angels grab Lot.
And so on and so forth.
In Genesis, it is not unusual for angels to physically interact with people. It's actually quite normal.
Additionally, in every instance of the Hebrew terms "sons of God" or bene Elohim, of the old testament, all instances are of angelic beings.
For example:
Job 1:6-7 NASB1995
[6] Now there was a day when the sons of God came to present themselves before the Lord, and Satan also came among them. [7] The Lord said to Satan, “From where do you come?” Then Satan answered the Lord and said, “From roaming about on the earth and walking around on it.”
Here, the sons of God are among Yahwey in heaven, at a divine meeting of a sort.
Or here:
Job 38:4, 7 NASB1995
[4] Where were you when I laid the foundation of the earth? Tell Me, if you have understanding,
[7] When the morning stars sang together And all the sons of God shouted for joy?
Here the sons of God are described as being present during creation.
Psalm 82:1, 6-7 ESV
[1] God has taken his place in the divine council; in the midst of the gods he holds judgment:
[6] I said, “You are gods, sons of the Most High, all of you; [7] nevertheless, like men you shall die, and fall like any prince.”
Here they are referred to as sons of the Most High, sons of God. And they are of the divine council, being judged that they may die like men, despite being Divine beings.
And so in Genesis 6, when it speaks of sons of God going into the daughters of mankind, we know that it is indeed referring to angelic transgressors.
Genesis 6:2, 4 ESV
[2] the sons of God saw that the daughters of man were attractive. And they took as their wives any they chose.
[4] The Nephilim were on the earth in those days, and also afterward, when the sons of God came in to the daughters of man and they bore children to them. These were the mighty men who were of old, the men of renown.
Just like is said in Jude 1:6-8 and 2 Peter 2:4-6