Genesis 3:15
ESV - 15 I will put enmity between you and the woman, and between your offspring and her offspring; he shall bruise your head, and you shall bruise his heel.
For follow-up discussion and general commentary on the topic. Comments are sorted chronologically.
The giants were most definitely the offspring of the fallen angles and my guess is they were RH negative blood type, like the royal family and many of our leaders today.