landing point to join his other jumper friends. “I’ve always roman-
ticized flying,” he told me later. “From the time I was 5 years old,
I just always wanted to fly. I can’t really explain it, it’s just part of
my DNA. It’s just something I need to do.”
Nick might not be too far off. Studies suggest that there’s
a strong genetic influence to sensation-seeking.^9 What is it about
his genetic makeup that might lead Nick to be a jumper and to see
the ground rushing up to him in a very different way than I would?The Genes of a High Sensation-Seeker
Chris and Jess (you’ll hear more about them later in the book) just
had a baby. As high sensation-seekers themselves, they are hoping
their new baby will inherit their love of rock climbing. Should they
load up their new baby registry with brightly colored plastic toy
carabiners and ascenders? Can we predict if the new baby will also
have a fondness for heights? Predicting behavior isn’t easy. In fact,
much of it is a mystery. Mostly we think of behavior as something
conscious, as when we choose what to wear from our closet or
where to go on vacation. But behavior can also be automatic or
even instinctual, like fear of falling from high places. This mix of
intentional and instinctual behaviors is impacted by our biological
makeup as well as environmental influences. Researchers in the
field of behavioral genetics study variation in behavior as it is
affected by genes. They study which differences among people
can be explained in terms of genetic and environmental
components.
Packed inside nearly all cells is a coded message. This mes-
sage is locked away in deoxyribonucleic acid, or DNA. There are
four nucleotide bases that make up your DNA: adenine, cytosine,
guanine, and thymine or A, C, G, and T. DNA contains the directions
to make every substance and structure in your body. There are more
than six feet of tightly bundled DNA in each of the body’s cells. In
essence, your DNA contains the unique list of ingredients and the
specific recipe to make youyou.Anyone who has watched a crime
drama lately knows that DNA is unique to every person who has
ever lived.
Every part of your body is produced from this instruction
manual, from earwax to endoplasmic reticulum and from toes to
tears. It’s the sum of your hereditary information, like an instruc-
tion manual for assembling your body. Your genes are the letters,33 / Born to Be WildDownloaded from https://www.cambridge.org/core. Access paid by the UCSF Library, on 11 Nov 2019 at 14:20:40, subject to the Cambridge