seeking, especially the disinhibition component, and especially in
males.
Clearly biological factors aren’t the only things that influ-
ence sensation-seeking. The environment plays an important role
too.Above Genetics: What You Do Can Also Change
your DNA
You can swap out many things in life – a salad for fries or even that
strange tie you got from your sister for one of your birthdays. One
thing you can’t? Your DNA. You’re pretty much stuck with the
genes you got at conception, some 38 weeks before you were
born. But there’s a bit more to the story.
The Human Genome Project was a 2.7 billion dollar
15-year effort to map out all the base pairs that make up
human DNA.^32 The Human Genome Project’s goal was to tran-
scribe those three billion base pairs in DNA and find out what
makes a human. But what they discovered was that even after
decoding all three billion letters, there was something missing.
Turns out that DNA sequences are just the beginning when it
comes to understanding genetic traits. Genetics simply deter-
mine what genes people have. But having a gene is just the
first step. A gene has to be turned on to be helpful and does
nothing if it’s silent or turned off. It seems as though not every
gene is activated and some genes can be switched off or silenced
bythebody.It’saprocesscalledmethylation,whereasmall
marker, just one carbon and three hydrogen atoms, is attached
to a section of DNA and switches it off. These changes don’t
involve changes in the specific gene sequences. What does that
mean? It means that the expression of that gene is changed
without changing the genetic code.
What can cause methylation? Lots of things: food, sleep,
exercise, and even our behaviors cause chemical modifications
around the genes that turn the genes on or off over time.^33
Epigenetics is the director of this process. If you think about our
DNA as the notes in a song, the notes may be the same, but how they
are played depends on their expression. The process of silencing the
gene is another layer on top of the genetic code, so it’s calledepi
(from the Greek “above”) genetics. The study of these kinds of
changes in genes is called epigenetics.46 / Buzz!Downloaded from https://www.cambridge.org/core. Access paid by the UCSF Library, on 11 Nov 2019 at 14:20:40, subject to the Cambridge