That is true. I forget where the verse is by citation, but it's at the end of the story where Abraham and Sarah go to a foreign country, and the king there finds Sarah beautiful, and Abraham is afraid that the king will kill him to take her if he says that she's his wife, so he "lies" and calls her his sister--only to later confess that she's really his half-sister.

I believe you are correct, they were related

added: found it Genesis 20: 12 - same father, different mothers

i think where Abraham tells the Pharaoh that she is his half-sister it is the truth in Genesis 12

Haran had just died before they took his daughters as wives. Abram then also took upon himself the care of his nephew Lot. Sarah was actually Abraham s niece. There was no law against that in the Old Testament. The information is in Gen 11:29 Sarai and Milcah were both daughters of Haran who was Abraham and Nahor s dead brother. Abram (Abraham) and Nahor are brothers and both married their nieces, Sarai (Sarah) and Milcah. In Gen 20:12 it states "not the daughter of my mother", meaning they did not come from the same womb, meaning they are not direct siblings. In Hebrew tradition sister can mean sister or niece.

Genesis 11:29

And Abram and Nahor took them wives: the name of Abram s wife was Sarai; and the name of Nahor s wife, Milcah, the daughters of Haran, the father of Milcah, and the father of Iscah.

Genesis 20:12

And yet indeed she is my sister; she is the daughter of my father, but not the daughter of my mother; and she became my wife.

no. she was his wife. maybe you read it in the qu'ran, they are known for lying