Final answer:
Judah's union with his daughter-in-law Tamar resulted in the birth of twins, Perez and Zerah, ensuring the continuation of his lineage according to the biblical account in Genesis.
Step-by-step explanation:
Judah's union with his daughter-in-law Tamar resulted in the birth of twins, named Perez and Zerah. This event is a part of Biblical history and is detailed in the Book of Genesis within the Old Testament.
In the Old Testament story, after the death of Tamar's husband and Judah's son, Er, Judah instructs his second son, Onan, to marry Tamar and produce an heir on behalf of Er. However, Onan fails to fulfill this duty, leading to his own death. Judah then promises Tamar that his youngest son, Shelah, would marry her once he grew up, but he did not follow through on this promise.
In an effort to secure her own future and that of her deceased husband's lineage, Tamar disguises herself and seduces Judah, resulting in her pregnancy. When Judah discovers that Tamar is pregnant, he initially orders her to be punished, until he learns that he himself is the father. She gives birth to twins, thus ensuring the continuation of Judah's lineage.