The role of nurturing in determining one’s behavioral traits has been

The role of nurturing in determining one’s behavioral traits has been hotly contested. Historically, geneticists believed that behavioral traits are inherited. After all, many properties of the brain are genetically organized and don't depend on information coming in from the senses. Since active genes are essentially inherited, most traditional geneticists believe that nurturing environment plays little role in shaping one’s behavioral traits.

However, a new line of research indicated that methyl groups can activate dormant genes, bringing about a slew of changes much later in a person’s life. The methyl group works like a placeholder in a cookbook, attaching to the DNA within each cell to select only those recipes - er, genes - necessary for that particular cell’s proteins, telling the DNA what kind of cells to form. The first such observation was in which methyl groups activated by causes ranging from exposure to certain chemicals to changes in diet set off a cascade of cellular changes resulting in cancer. Because methyl groups are attached to the genes, residing beside but separate from the double-helix DNA code, their study is dubbed epigenetics - “epi” referring to Greek for outer or above.

Behavioral geneticists, encouraged by this discovery proved that traumatic experiences such as child neglect, drug abuse, or other severe stresses also set off epigenetic changes to the DNA inside the neurons of a person’s brain, permanently altering behavior. Similarly, through multivariate analysis, they proved that identical twins, in scenarios where one twin has gone through a life altering event, can have vastly different reaction to a stressful situation.

Notes: Old thot: Behav Trait(BT) Inherited,
Reason- Many brain properties inherited and not thru senses.
Active genes responsible for BT.
Therefore, nurturing Env plays little role in shaping BT.

New Research- Methyl Activates Dormant genes.
Cell has DNA, DNA has Methyl group, which tells DNA what kind of new cells to form.

Result-Methyl grup activates, Reasons- Exposure or Even diet change(cancerous)

Traumatic xperience also cause changes to DNA thus Altering behavior.


1. The primary purpose of the passage is to

A. propose a new framework that incorporates the role of genetics and the role to life experiences in determining an individual’s behavioral traits-NO, author doesnt propose. He presents.
B. summarize the new research on behavioral traits and inheritance-No, he doesnt summarize, he presents.
C. present findings indicating that, like inheritance, nurturing plays a role in shaping one’s behavioral traits-Correct, Matches our pre-thinking.(inheritance and nurturing play a role in BT)
D. argue through new findings that life experiences play a vital role in shaping an individual’s behavioral traits-No, life experiences play a vital role but author doesnt discard inheritance fully.
E. establish a causal relationship between an individual’s life experiences and his reaction to stressful situations-Out of scope, too specific.



2. Why does the author state highlighted text:

A. to provide a reason for geneticists belief that behavioral traits are inherited- Correct, preceding line tells the fact.
B. to prove that active genes and not dormant genes define key behavioral traits.-Out of scope.
C. to describe the role played by genetic inheritance in determining one’s personality-No, It doesnt describe the role.
D. to indicate that there have been few experiments in the past linking behavior and life experience-No, nothign about few experiments is mentioned
E. to lay the foundation for the development of epigenetics-Out of scope.



3. Which of the following may be inferred from the passage?

A. It is quite likely for twins to develop different personality traits- No, not quite likely. Only in the event when one of them has gone thru a life altering experience
B. Resetting the changes introduced by corresponding methyl groups can help cure cancer-No, Mthyl group ataching to DNA due to diet changes may cause cancer but detaching it will undo cancer is no where to be found and thus cant be inferred. What if cancer is irrevocable?
C. Most cancers are caused due to one’s life experiences rather than due to one’s genetic make-up-No, Not always.
D. Traumatic experiences that activate dormant genes can bring about behavioral changes.-Correct, Trauma can bring BT.
E. Identical twins who have led different lives are likely to have different behavioral traits.