Chronologically we have the first mention of the angelic realm in Job 38:7 when God laid the foundation of the Earth and "the morning stars [Michael and Lucifer] sang together, and all the sons of God [the holy angels] shouted for joy". We could thereby easily surmise that their first estate, or home, was in the heavens. Their social ranking was also affected, as we shall see, as originally all the angels were created holy.
Noticing that all the above are of the male gender, the creation of Eve and the advent of the female sex became a snare to many of them, often referred to as fallen angels, no doubt, after their leader, one of the two "morning stars" as we read in Isaiah 14:12, "How art thou fallen from heaven, O Lucifer, son of the morning! how art thou cut down to the ground [Earth], which didst weaken the nations!"
Apparently the angels were given permission to materialize in order to try their hand at restoring the human race after the sin of disobedience prohibited Adam and Eve from remaining in the Garden of Eden. As messengers between heaven and earth materialization was permitted on a regular basis, but for some of the angels the beauty of womankind was too temptind and they succumbed to a "permanent" residence on the Earth as described in Genesis 6:2, "The sons of God saw the daughters of men that they were fair; and they took them wives of all which they chose."
These spirit nature fathers and their human nature wives produced giant children (Gen. 6:4) which caused so much evil in the earth (Gen. 6:5-13) that God decided to destroy it and spared only Noah and his immediate family. The giant offspring of the fallen angels were drowned along with all the rest of the human family, but the angelic fathers escaped by de-materialization and, since they were forbidden to return to heaven, they were confined to Earth's atmosphere by what power of God–called chains of darkness– we can only surmise.