Twice, in Genesis, Abraham declared that Sarah was his half-sister. But
Gen 11:31 Terah took Abram his son and Lot the son of Haran, his grandson, and Sarai his daughter-in-law, his son Abram's wife, and they went forth together from Ur of the Chaldeans to go into the land of Canaan, but when they came to Haran, they settled there. (ESV)
This passage clearly mention that Sarah was not Terah's daughter!!
Gen 11:31 Terah took Abram his son and Lot the son of Haran, his grandson, and Sarai his daughter-in-law, his son Abram's wife, and they went forth together from Ur of the Chaldeans to go into the land of Canaan, but when they came to Haran, they settled there. (ESV)
This passage clearly mention that Sarah was not Terah's daughter!!