I think giants existed prior to the angelic offspring theory if I am reading this right.
"There
were giants in the earth in those days; and
also after that, when the sons of God came in unto the daughters of men, and they bare children to them, the same became mighty men which were of old, men of renown.
5 And God saw that the wickedness of man was great in the earth, and that every imagination of the thoughts of his heart was only evil continually.
6 And it repented the LORD that he had made man on the earth, and it grieved him at his heart."
The Lord wiped out the entire population of people from the earth other than 8 on the ark. However, it did nothing to deal with the so called giant interspecies kind AFTER the flood either.
If there's no rare genetic variability for size differences unless reproducing with angelic kinds, I wonder if the NBA should have genetic testing done to see if they are half angel?