Why does the Torah bring us so much background information about Elisheva, listing who her father and brother were?

According to Eben Ezra, the Torah specifically mentions that she is the sister of Nachshon to teach us about the secret of the Kehuna (priesthood). The children of Aharon had special “yichus”, in other words they came form a good family, from their mother’s side as well, since Elisheva was the sister of Nachshon the son of Aminadav, the nasi (prince) of the tribe of Yehuda.

Ramban says that Elisheva, the mother of the Kehuna is the sister of the most important nasi.

Sforno says that Nachson was the most important nasi of his generation and Elishava was the mother of important people who would later become the Kohanim.

A lot of people feel that when choosing a spouse their yichus is important.

It says in Masechet Yoma 85a: Rabbi Yochanan said: “Whoever is a Talmid Chaham and his son is a Talmid Chacham and his grandson is a Talmid Chacham, the Torah will never stop from his descendents.”

The problem is that we can’t only rely on yichus. A person can have wonderful ancestors, but they must continue to follow in their footsteps.

Unfortunately, two of Aharon’s sons, did not follow in Aharon and Elisheva’s footsteps and were put to death by God. As it says in Vayikra 10:1-2: “And Nadav and Avihu, the sons of Aharon, took each of them his censer and put fire in it and put incense on it and offered strange fire before God which he commanded them not. And a fire went out from God and devoured them and they died before God.”

We read in Midrash Raba 20:10: “Rabbi Levi said: Nadav and Avihu were conceited. Many women wanted to marry them but they said: Our uncle is King (Moshe), our other uncle is head of a tribe (Nachshon), our father (Aharon) is the Kohen Gadol (High Priest) and we are his two assistants. Who could possibly be worthy enough to marry us?”

We learn from here that our yichus is only as good as the effort that we put in to cultivate the next generation.