In the very beginning of earth’s history, there was no disobedience to God’s law originally when close relatives, first cousins, or even brothers and sisters to marry each other. Adam and Eve’s sons and daughters married each other.
In the patriarchal era, Abraham married his half-sister (Genesis 20:12). And God blessed this union to produce the Hebrew people through Isaac and Jacob. Isaac also asked his son to marry his cousin saying, “You shall not take a wife from the daughters of Canaan. Arise, go to Padan Aram, to the house of Bethuel your mother’s father, and take yourself a wife from there of the daughters of Laban your mother’s brother” (Genesis 28:1, 2).
In the Mosaic era, marital laws changed. According to Leviticus 18:6-18, a man was forbidden to marry the following: daughter, stepchildren, aunt, sister or half-sister, stepsisters, daughter-in-law, granddaughter, and step-granddaughter. You will notice that cousins are not included in the list.
Why where the marital laws changed?
God gave Moses these laws to protect them from the accumulated deformity of genes. Adam and Eve did not have any genetic defects, and that enabled them and the first few generations of their descendants to have a far better genetic pool than we do now.
Today, the marriage of close family members could result in genetic abnormalities because there is a high risk of their recessive characteristics becoming dominant. However, when people from different families have children, it is highly unlikely that both parents will carry the same recessive traits.
The United States of America is the only nation in the world with legal restrictions against first cousin marriages. Around half of the states allow first cousin marriage either without restrictions or under certain specific circumstances. So, if you are a resident of the United States of America, you need to find out whether your union would be legal in the state where you live.
In any case, you need to take the matter before the Lord in prayer for it demands serious attention.
In His service,