The Mystery of
Twins
By: Mirella Cabrera
Psychology Per.7
Mc Elmoyl
• Scientists are interested in twins who were separated at
birth because they observe the many similarities even
though they don’t live together. They like to focus on
their environment, traits, genes, personality, abilities,
intelligence, and many other characteristics that a normal
person would have just that this time two people that are
alike have it. For example, psychologist Thomas
Bouchard studied James and James who were separated
at 3 weeks of age.
Why are scientists interested in
twins who were separated at birth?
• First of all, a scientist should begin his or her studies by
asking for permission to use that person as an experiment
or simply just to ask questions of their personal life.
• Then, continue with the study by using only the
information given by the person; if the one twin don’t
know about the other it is impossible to gather much
information because a scientist must take opinions from
both sides or known better, both twins.
What steps should be taken by
scientists studying twins to avoid
possible invasions of privacy?
• Twins who come from one fertilized egg share the same
placenta throughout the 40 weeks of pregnancy. These
twins will have the same heredity which means that they
will look the same. Because they develop from a single
fertilized egg (a single zygote), identical twins are called
monozygotic.
Identical Twins
1. Dichorionic-Diamniotic: Twins that have two separate
chorions and amniotic sacs.
2. Monochorionic-Diamniotic: Twins that share the same
placenta and usually have two amniotic sacs.
3. Monochorionic-Monoamniotic: These twins also share
the same placenta which can lead to the babies umbilical
cords tangling within one another.
4. Conjoined Twins: Twins who are born stuck together
and share the same organs.
4 different ways that identical
twins can develop in the uterus…
Twins who come from two
different eggs which are
fertilized by two different
sperm cells. Their genes
are not more similar than
the ones of brothers or
sisters. “Since fraternal
twins are from separate
eggs, like brothers or
sisters from single births,
they share only 50% of
their genes.” Fraternal
twins are called dizygotic.
Fraternal Twins
•
•
According to
psychologist Dr.
Nancy L. Segal, virtual
twins are unrelated
kids born within nine
months between each
other and enter a
family, through birth or
adoption.
She states, “Raised
together essentially
from birth, or at least
since infancy, virtual
twins may be genetic
strangers, but they
share an environment
from an early point in
life.”
Virtual Twins
• Due to twins who are separated at birth, the environment
has a big impact in their way of being and acting. Claire
M.A. Haworth, Philip Dale, and Robert Plomin did a
study and on twins and stated, “Environmental influences
were mainly of the non-shared variety, suggesting that
children from the same family experience school
environments differently.”
Influence of the
Environment
• Genes interact within the twins in such way, or so it is
said by Kristen Jacobson; PhD, “Other studies of
monozygotic twins have identified variations in DNA
methylation levels in certain target gene prompter
regions.”
• American Psychological Association has concluded that,
“Not only are both genes and environments important for
both normal and abnormal human development, but genes
and environment operate interactively to produce both
risk and resilience to specific behavioral and psychiatric
disorders.”
Interaction of Genes
• Due to the New York Times article, “Although there has
been wide press coverage of pairs of twins reared apart
who met for the first time in the course of the study, the
personality results are the first significant scientific data
to be announced.”
• What this means is that the genes in twins are quite the
same. Their personality traits, emotions, intelligence, etc.
Between genes and environment, genes take a major role
in determining personality traits because you are born
with that character.
• Environment within we all live in depends on the way we
act upon many things. Twins personality traits, emotions,
and intelligence mainly depend on their environment. It is
known to be the main cause in which personality is
different in every person but not quite different in twins.
• Study of identical twins who were raised in different
environments.
• In 1979, the Minnesota Center for Twin and Adoption
Research (MICTAR) began a study to determine the
degree to which heredity influences personality traits and
intelligence.
University of Minnesota
• In this article, it talks about two twin boys that were born in
Ohio and were then given to adoption being only 3 weeks old.
They were both adopted by different parents who lived 50
miles apart. Both parents knew that their child had a twin, but
what they didn’t know was that the other twin was actually
alive. It states that, “Both boys were independently named
James by their adopted parents. Neither knew he had a twin.
Both were great at math and bad at spelling.” During their
childhood, they both had a dog named toy. While growing up,
both became sheriffs, bought little blue Chevy's, got migraines,
married a women named Linda which then they both got
divorced and married a women named Betty. Once they turned
39, the record search program reunited them.
“Two Twins Separated at Birth
Live Almost Identical Lives”
• These two twins were separated as babies. In the 1930’s
in Europe, Stohr grew up in Germany and joined the
Hitler Youth while Yufe was raised as a Jew and moved to
Israel. In the article it says, “Yet, despite being as
different as two human beings can be, when they met in
their 50’s they found that they spoke alike, liked the same
foods, and shared oddly specific habits, like wearing
rubber bands on their wrists or flushing the toilet before
using it.”
Oskar Stohr and Jack Yufe
• These two twins are known as virtual twins; Sara being
adopted at birth. The parents of these girls had tried so
many times to have a child of their own but just didn’t
seem to work out. They decided to adopt a child being
Sara and after adopting her, a month later, their mom
became pregnant of Julie. The problem was that as they
grew older, their genes began to play a major role due to
their way of being and personality traits. For example,
Sara goes to church; Julie don’t, Sara loves to talk; Julie
is really quiet, and Sara wears glasses; Julie wears
contacts.
Sara and Julie Curry
• "Two Twins Separated at Birth Live Almost Identical
Lives." RSS. N.p., n.d. Web. 31 Oct. 2013.
• "5 Real-Life Stories of Twins." Cracked.com. N.p., n.d.
Web. 31 Oct. 2013.
• "AirTalk." KPCC. N.p., n.d. Web. 31 Oct. 2013.
• NCBI. U.S. National Library of Medicine, n.d. Web. 05
Nov. 2013.
• "Considering Interactions between Genes, Environments,
Biology, and Social Context." Web. 05 Nov. 2013.
Resources