My family believes that it is a sin to marry a person who is not the same nationality as you. As an example, they believe that is wrong to marry someone who is Mexican, Italian, Indian, etc. Being white, they also believe that it is a sin to marry someone that is black. When I ask them how they justify this belief they reference the Tower of Babel, but I do not think that is correct because God did not destroy the Tower of Babel for that reason. Are there any Bible verses that justify my family's belief?
The tower of Babel is evidence that all people come from the same stock. "And He has made from one blood every nation of men to dwell on all the face of the earth, and has determined their preappointed times and the boundaries of their dwellings" (Acts 17:25). Israel had restrictions against marrying seven specific nations because of their idolatry, but that doesn't carry over into Christianity. There is no restriction on whom a Christian marries in regards to nationality or skin color. There are sensible aspects, such as marrying someone who will encourage you to be a better Christian, but that is a matter spiritual faith, not physical attributes.
As a counter example, "Then Miriam and Aaron spoke against Moses because of the Ethiopian woman whom he had married; for he had married an Ethiopian woman" (Numbers 12:1). Ethiopians are dark skinned and Israelites are light skinned. Ethiopia and Israel were two different nationalities.
Other examples of people marrying different nationalities are Salmon (Israelite) and Rahab (Canaanite), Ruth (Moabite) and Boaz (Israelite), and Uriah (Hittite) and Bathsheba (Israelite). Timothy's father was a Greek and his mother was an Israelite (Acts 16:1).
Thank you for your response! I value your answers dearly and this really clears things up.