I've been asked about the Giants that the KJV infers were the sons of God and that they went into the daughters of men and the women bore them children. Below are a group of text from different sources that may help people answer this question for themselves.
KJV Gen 6:4 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.
[Judaic] Genesis 6:4 states "The Nephilim (KJV uses the word Giants) were on the earth in those days --and also afterwards-- when the sons of God went to the daughters of men and had children by them. They were the heroes of old, men of renown." The Nephilim were a race of giants that were produced by the sexual union of the sons of God (presumably fallen angels) and the daughters of men. Translated from the Hebrew texts, "Nephilim" means "fallen ones." They were renowned for their strength, prowess, and a great capacity for sinfulness. The origination of the Nephilim begins with a story of the fallen angels. Shemhazai, an angel of high rank, led a sect of angels in a descent to earth to instruct humans in righteousness. The tutelage went on for a few centuries, but soon the angels pined for the human females. After lusting, the fallen angels instructed the women in magic and conjuring, mated with them, and produced hybrid offspring: the Nephilim. The Nephilim were gigantic in stature.
Easton's 1.) Heb. nephilim, meaning "violent" or "causing to fall" (Gen. 6:4). These were the violent tyrants of those days, those who fell upon others. The word may also be derived from a root signifying "wonder," and hence "monsters" or "prodigies." In Num. 13:33 this name is given to a Canaanitish tribe, a race of large stature, "the sons of Anak." The Revised Version, in these passages, simply transliterates the original, and reads "Nephilim." (2.) Heb. rephaim, a race of giants (Deut. 3:11) who lived on the east of Jordan, from whom Og was descended. They were probably the original inhabitants of the land before the immigration of the Canaanites. They were conquered by Chedorlaomer (Gen. 14:5), and their territories were promised as a possession to Abraham (15:20). The Anakim, Zuzim, and Emim were branches of this stock. In Job 26:5 (R.V., "they that are deceased;" marg., "the shades," the "Rephaim") and Isa. 14:9 this Hebrew word is rendered (A.V.) "dead." It means here "the shades," the departed spirits in Sheol. In Sam. 21:16, 18, 20, 33, "the giant" is (A.V.) the rendering of the singular form ha raphah, which may possibly be the name of the father of the four giants referred to here, or of the founder of the Rephaim. The Vulgate here reads "Arapha," whence Milton (in Samson Agonistes) has borrowed the name "Harapha." (See also 1 Chron. 20:5, 6, 8; Deut. 2:11, 20; 3:13; Josh. 15:8, etc., where the word is similarly rendered "giant.") It is rendered "dead" in (A.V.) Ps. 88:10; Prov. 2:18; 9:18; 21:16: in all these places the Revised Version marg. has "the shades." (See also Isa. 26:14.) (3.) Heb. 'Anakim (Deut. 2:10, 11, 21; Josh. 11:21, 22; 14:12, 15; called "sons of Anak," Num. 13:33; "children of Anak," 13:22; Josh. 15:14), a nomad race of giants descended from Arba (Josh. 14:15), the father of Anak, that dwelt in the south of Palestine near Hebron (Gen. 23:2; Josh. 15:13). They were a Cushite tribe of the same race as the Philistines and the Egyptian shepherd kings. David on several occasions encountered them (2 Sam. 21:15-22). From this race sprung Goliath (1 Sam. 17:4). (4.) Heb. 'emin, a warlike tribe of the ancient Canaanites. They were "great, and many, and tall, as the Anakims" (Gen. 14:5; Deut. 2:10, 11). (5.) Heb. Zamzummim (q.v.), Deut. 2:20 so called by the Amorites. (6.) Heb. gibbor (Job 16:14), a mighty one, i.e., a champion or hero. In its plural form (gibborim) it is rendered "mighty men" (2 Sam. 23:8-39; 1 Kings 1:8; 1 Chr. 11:9-47; 29:24.) The band of six hundred whom David gathered around him when he was a fugitive were so designated. They were divided into three divisions of two hundred each, and thirty divisions of twenty each. The captians of the thirty divisions were called "the thirty," the captains of the two hundred "the three," and the captain over the whole was called "chief among the captains" (2 Sam. 23:8). The sons born of the marriages mentioned in Gen. 6:4 are also called by this Hebrew name.
I hope this gives those with this question some place to research the subject.
Just An Old Preacher
Rev Robert Fuller