Is personality fixed?

When meeting with b-mitzvah families, I often explore the question “Why 13?” We look together at various texts from our tradition about age 13 and how they shed light on the meaning of b-mitzvah. One of the sources comes from this week’s parashah, Genesis 25:27: “When the youths grew up, Esau became a man who knows the hunt, a man of the field, and Jacob was a simple man, dwelling in tents.” Rashi elaborates: “While they were children, their deeds were not distinguishable from each other, and each one’s nature could not be determined. Once they became 13, however, one went to the house of study and the other to idolatry.

In other words, by age 13, the twins’ essential natures became apparent. Their personalities were solidified. I like to ask the 12-year-olds if they think their personalities are established by this age. Do they believe their essential nature will always be what it is now?

It is striking to me how the rigid description of Jacob’s and Esau’s personalities is undermined in the parashah itself and the Biblical commentators’ glosses. Let’s look at each twin on his own, starting with Jacob, called a “simple man.” Rashi interprets it this way: “One who is not good at deceiving is called simple.” As the story unfolds, Jacob becomes fairly expert at just that — deception. Luring Esau into selling his birthright and tricking Isaac into blessing him with the firstborn blessing are two key instances of Jacob’s skillful cunning. Once he realizes what Jacob did, Isaac says plainly to Esau: “Your brother came with deception.” (27:35) The one who was “simple” at age 13 has become the opposite.

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Similarly, Esau’s nature departs from the initial characterization. Esau is described as “a man who knows the hunt,” which 13th-century French rabbi Hizkuni interprets as “being skilled in deception, for one cannot hunt for a beast without trickery.” And yet Esau becomes not a deceiver, but a victim of master manipulation by his twin. Indeed the language that Esau uses is simple and direct: “He (Jacob) took my birthright and now he has taken my blessing.” The conniving one is Jacob, not Esau.

Psychologists used to believe that personalities were fixed throughout adulthood. But over the past 30 years, cross-sectional and longitudinal studies have demonstrated that personality traits evolve substantially throughout the adult lifespan. In a meta-analysis of more than 90 studies, researchers pinpointed ages 20-40 as the time when changes in personality occur most often. Interestingly, the Torah specifies that the twins were 40 years old shortly before Jacob deceived Isaac. (26:34)

Our essential natures are not immutable. While certain personality traits come to light as we enter adolescence, we continue to evolve. Circumstances and experiences may call upon us to develop new strengths and habits which in turn shape who we are. A personality that seems to solidify at age 13 does not determine who we will be for the rest of our lives. I, for one, am thankful for that. PJC

Rabbi Amy Bardack is the rabbi of Congregation Dor Hadash. This column is a service of the Greater Pittsburgh Jewish Clergy Association.