On the words, “These are the descendants (Toldos) of Yitzchak,” Rashi comments, “These are Ya’akov and Eisay mentioned in the Parsha.”
According to Chasidic teachings, Ya’akov represents the soul, and Eisav, the body. The Parsha is thus named after both Ya’akov and Eisav, because the soul and the body each have their own exclusive qualities.
The soul is described as a “child” of G-d, because the love shared between the soul and G-d is a natural type of love, resembling the parent-child relationship.
The body, on the other hand, has no inherent love for G-d – on the contrary, it conceals G-d’s presence. But, ironically, when G-d “chose” the Jewish people, He chose primarily our bodies. For, it would not have been an act of true self-expression to choose the Jewish soul, since anybody would choose a superior product over an inferior one. Rather, it is the Jewish body, which appears to be quite similar to that of the non-Jew ,that was selected by G-d (See Tanya, ch.49).
Of course, this does not mean to say that the soul was not chosen by G-d at all. It is only that the body has no redeeming feature of its own other than the fact that it was chosen by G-d – so its chosenness “stands out” more than in the case of the soul.
When soul and body are together, each begins to learn from the other’s unique quality: Through observing Torah and mitzvos, the soul teaches the body how to love G-d; the body, in turn, teaches the soul how to reveal its chosenness.
And that is why Ya’akov, the soul, and Eisav, the body, are both “mentioned in the Parsha.”
(Based on Sichas Shabbos Parshas Toldos 5752)