Michael G. Hasel
And Cain had relations with his wife and she conceived, and gave birth to Enoch. Genesis 4:17.
The mention of Cain’s wife seems to create a problem. Where did she suddenly come from? The earliest inhabitants of earth obviously had no other choice but to marry their brothers and sisters. This custom raises the question whether God intended incest from the beginning in order for the earliest human beings to carry out His instruction to be “fruitful and multiply and fill the earth” (Gen 1:28).
Marriage between close relatives – Adam and Eve did indeed have other sons and daughters (Gen 5:4) the latter of which Cain and Abel must have married.1 This practice was inevitable in the second generation. In the third generation, marriage could have taken place between first cousins and by the fourth generation through second cousins. Since Adam and Eve came perfect from the Creator’s hand, the danger of birth defects through inbreeding at this stage of human history did not exist, despite the entrance of sin.
Even a long time after the Flood, we find that Abraham married his half-sister Sarah. During the sojourn when the children of Israel were in Egypt, it was common in the Egyptian royal family for marriages to take place among siblings. For example, in the time of Moses, during the eighteenth dynasty, Hatshepsut married her half-brother Thutmose II. Among the Israelites, we find that Moses’ father Amram married a young aunt, his father’s sister, Jochebed (Exod 6:20). Such marriages were viewed very differently in those ancient cultures.
However, after God called Israel out of Egypt and set them apart as a holy nation of priests (Exod 19:6; Lev 19:2), Israel received laws governing all forms of incest (Lev 18:7-17; 20:11, 12, 14, 17, 20, 21; Deut 22:30; 27:20, 22, 23). While in Egypt such practices were common; the Israelites in their new land were to avoid these customs of pagan societies. Leviticus 18:6 prohibits sexual relationships with close relatives such as a mother, father, stepmother, sister, brother, half-brother, granddaughter, daughter-in-law, son-in-law, aunt, uncle, or a brother’s wife. What had once been permitted out of necessity was now forbidden. As a holy nation they were called to a high standard of moral living that would distinguish them from the nations around them. The specific sexual prohibitions must be viewed in terms of the conditions that prevailed in the ancient Near East at that time. The worship of the various fertility goddesses among the nations made “the abandonment of one’s body to various sensual pleasures a religious obligation.”2 By contrast, the Israelites were to consecrate themselves to Yahweh and reflect His holiness to the nations around them (Exod 19:2; Isa 49:6).
Conclusion – While at the beginning of human history marriage among relatives was a necessity, by the time Israel became a nation sexual relations between close relatives was prohibited. The reason for this prohibition was primarily because of their special status as God’s holy people but also because the danger of genetic damage increased as the effects of sin became more pronounced. This danger was not present immediately after the Creation. God had created all things perfect. While today the risk of genetic damage is extremely high, the early generations of human beings did not face the same biological risks.
1 “We must assume that Cain’s wife was one of Adam’s ‘other daughters’ (Gen 5:4). Later sibling marriage was unnecessary, and it was soundly denounced in Mosaic tradition (e.g., Lev 18:9)” (K. A. Matthews, Genesis 1-11:26, The American Commentary [n.p.: Broadman and Holman, 2002).
2 A. Noordtzij, Leviticus, Bible Student’s Commentary (Grand Rapids, MI: Zondervan, 1982), 181.