Genetic Linkage to Picky Eating

 A study published by Zeynep Nas, Moritz Herle, and fellow authors revealed a high possibility of genetic linkage to food fussiness in children. Their article, "Nature and nurture in fussy eating from toddlerhood to early adolescence: findings from the Gemini twin cohort," was published on September 19, 2024, discussing the researchers' study on twin toddlers and food pickiness.

Researchers studied sets of twin children, and parents were asked to answer a series of a questions about their childrens' eating habits, home environments, and health. These survey answers were filtered by identical twins, who had identical sets of DNA, and nonidentical twins, who shared less DNA. Researchers found that identical twins had a much higher rate of trait similarity, in terms of food pickiness, compared to nonidentical twins. Thus, it was concluded that food fussiness did in fact have genetic influence, in addition to environmental influence, which were more apparent and significant later in children's lives.

Nas and Herle's publication gives us a better insight on the causes of food pickiness. It is rather unique and fascinating since it suggests a genetic cause, rather than purely environmental. Hence, this research may be important for parents and caregivers who struggle with food fussiness in children, and whom wish to learn more about the subject. As the article states, a better understanding of food pickiness being a heritable trait may help alleviate psychological distress on parents or benefit a child's well-being.

ARTICLES:

https://acamh.onlinelibrary.wiley.com/doi/10.1111/jcpp.14053

https://www.genome.gov/genetics-glossary/identical-twins

https://www.psychologytoday.com/us/blog/scientific-mommy/202401/the-emotional-strain-of-picky-eating

Research Finds Shared DNA Signature of Identical Twins

Identical siblings are used to sharing a lot with their twin, including their DNA. But new research suggests that they also share a distinct marker of their twin status, not encoded within their DNA, but rather on it. This marker is found within the epigenome, consisting of chemical tags along the DNA that regulate gene activity without changing the genetic sequence. Researchers discovered that identical twins universally exhibit a common set of these markers, which remains consistent from birth through adulthood. 

The shared epigenetic markers can help identify individuals who were conceived as identical twins but lost their sibling in the womb or were separated at birth. This research lays the groundwork for understanding the process of monozygotic twinning, which remains a mystery despite its long-standing fascination. Identical twins form when a fertilized egg splits into two embryos, a process with unknown triggers. Jenny van Dongen, an epigeneticist at Vrije Universiteit Amsterdam, says the biological process that generates twins “is an enigma.”

During early development, both twins and non-twins undergo numerous epigenetic changes that activate or deactivate genes as the embryo forms. Some of these changes might explain minor distinctions between identical twins. So to better understand what makes a zygote split to form identical twins, “it makes sense to look at epigenetics,” van Dongen says.

By analyzing over 450,000 genomic sites in nearly 6,000 monozygotic and dizygotic twins, they compared identical twins with fraternal ones, eliminating influences from shared womb experiences. They identified 834 spots where identical twins exhibited remarkable similarity in epigenetic marks, particularly in centromere and telomere regions and near genes governing early developmental processes, like cell adhesion regulation. The health implications of these differences remain uncertain. These shared epigenetic patterns were consistent across twins of various ages and geographical locations- and even in different cell types. The researchers developed a test with an 80 percent accuracy rate to identify identical twins, including those affected by vanishing twin syndrome or separated at birth.

“This is a very, very important finding that opens up a lot of avenues of inquiry,” says Segal, the developmental psychologist. For example, identical twins are predisposed for a variety of conditions, from left-handedness to certain congenital disorders such as spina bifida, where the spine fails to develop properly. Perhaps, for some portion of people, these conditions stem from being an unknown identical twin, she says. 

Genetic research, and quite frankly all research, regarding twins always seems so interesting! It's quite cool how twins have piqued interest across cultures and traditions throughout history- and it’s even cooler to see how science develops deeper into understanding twins and the biological mechanisms behind it. 

Sources: 

https://www.nature.com/articles/s41467-021-25583-7

https://www.sciencenews.org/article/identical-twin-siblings-common-set-chemical-markers-dna-epigenetics

Can I Have Twins Even If They Don't Run in my Family?

  This article discusses the role of genetics in determining the probability of having twins. It explains that the likelihood of conceiving twins is influenced by both genetic and environmental factors. Monozygotic (identical) twins occur when a single fertilized egg splits into two embryos, while dizygotic (fraternal) twins occur when two separate eggs are fertilized by two different sperm cells. While the occurrence of monozygotic twins is generally not strongly linked to genetics, dizygotic twinning is more likely to run in families. Factors such as hyperovulation, maternal age, ethnic background, and assisted reproductive technologies can also influence the chance of having twins. Additionally, the article provides references to scientific journal articles for further reading on the topic. I found this article very interesting because I always thought that fraternal and identical twins were essentially the same thing, both running in families. I think lots of people believe this too, because I have heard people saying identical twins run in their family. This article disproves this though, basically saying that while fraternal wins usually can be traced back a few generations, identical twins are just a really cool magic trick that occurs during pregnancy and can really happen to anyone regardless of their family line!

 

Sources : 

1. https://medlineplus.gov/genetics/understanding/traits/twins/

2. https://pubmed.ncbi.nlm.nih.gov/18024802/

Does Exercise Alter how Gene's Behave?

 Identical twins can often develop differing diseases throughout their lifetime according to a new study. One of the main determinants of this is how physically active each twin is during their lifetime. An exercise study was done on 70 sets of twins over the course of seven years. Activity trackers were given to each participant to track their activity levels. It found that the twin with higher physical activity levels  showed lower signs of metabolic disease. Since twins have nearly identical genes, this would indicate that there were likely epigenetic changes for the more active twin. Epigenetics is the study of how your environment and your behaviors can change the way your genes function. The epigenetic markers for the more active twin showed that they were linked to having a lower metabolic syndrome, which is a condition that can lead to having type 2 diabetes, heart disease, etc. There were also epigenetic changes noted for the more physically active twins BMI and waist size.  Thus proving that we do have some say in the diseases and health problems people often face in old age. Something as simple as taking a 30 minute walk everyday could have life altering effects down the road. Hopefully this study will encourage people to stay more physically active and to also realize their daily behaviors have a huge say in their health.

He Jiankui shocked the world of genetics

He Jiankui shocked the world of genetics

Yes, I am very late to this party. The article I am writing about was published in Time on November 29th,

2018, a whole year ago. However, I was very shocked by the article, and thought it was worthy to share.

He Jiankui, a professor at the Southern University of Science and Technology, used CRISPR on embryos

against all ethical standards. The babies produced from the treat go by Lulu and Nana, and were intended

to be treated with CRISPR to disable a gene that helps HIV enter healthy cells. I think the most shocking

thing is that is performed the technique behind everyones back, against strict advice. Many problems

could arise from using CRISPR on human embryos, but He definitely has the guts to try. The only thing

left to do now is sit back and watch. The twins will forever be the focal point of every genetic

advancement from here on out. I am very interested to see what results occur.

https://time.com/5466967/crispr-twins-lives/

Related article:

https://www.sciencemag.org/news/2019/08/did-crispr-help-or-harm-first-ever-gene-edited-babies

Genetics Influence on Depression

Genetics Influence on Depression

 At least ten percent of people in the US will experience major depressive disorder. This number is two times more evident within women rather than men. Going against the majority of the stigma that society manifests toward depression, in most cases the cause of depression has been linked to be about 50% genetics. In order to study the heritability of major depression within a family, scientists seek twins. If genes are a part of the cause and a patient has an identical or fraternal twin, then the identical twin would be at higher risk than the fraternal twin. This is due to the percent of genes in common being double amongst identical twins. This experiment lead many scientists to predict that the heritability of major depression is probably about 40 to 50 percent. Further tests have been done as well leading to roughly the same conclusion. For example, a British research team isolated a gene that appears to be evident in multiple family members that have been diagnosed with depression. As a result of this experiment the chromosome 3p25-26 was found in more than 800 families with recurrent depression. Even on a bigger scale, the results of a genome wide meta analysis of genetic data from 807,553 individuals (246363 cases and 561,190 controls) linked 102 genetic variants and 269 genes to depression. These numbers were then validated in an independent sample of another 1,507,153 individuals. Then within gene set analysis MAGMA* identified 269 putative genes** and 15 gene sets that were associated with depression, along with the connection between prefrontal brain regions and their role with depression. All of these experiments concluded to roughly the same ending; depression has a genetic factor along with its environmental factors. Its genetic factor is definitely not simple and is believed to be a combination of genetic changes that predispose some people to become ill, not just a single gene. Meaning that no one can “inherit” depression from their mom or their dad, it goes a lot deeper than that. Each person inherits a combination of genes from mom and dad and these combinations can potentially lead to diseases such as depression. 

          Overall, in my opinion these studies are crucial to breaking the stigma against depression. People must stop blaming those who are suffering already. In fact it has been found that depression is the leading cause of disability worldwide and is estimated that 1 in 6 people will develop depression during their lifetime. With this being said, you know someone who is struggling whether they have come forward about it or not. This information prioritizes the fact that society must unwarp their opinions toward depression. Being scientifically researched and proven to have another reason other than “I’m just sad” has to eventually have an effect on breaking the stigma against depression. People are not simply just lazy, it’s not always their fault. Try telling a cancer patient to stop having cancer. 

a segment of DNA whose protein and function is unknown**

a genetic analysis tool*

http://med.stanford.edu/depressiongenetics/mddandgenes.html

Genetics of Brain Function. “Major Depression and Genetics.” Genetics of Brain Function, 

        med.stanford.edu/depressiongenetics/mddandgenes.html.

https://www.healthline.com/health/depression/genetic#outlook

Faris, Stephanie. “Is Depression Genetic or Environmental?” Healthline, Healthline Media, 25   

        July 2017, www.healthline.com/health/depression/genetic#outlook.

https://www.genengnews.com/news/genetics-of-depression-linked-with-hundreds-of-genes-and-different-behavioural-traits/

“Genetics of Depression Linked with Hundreds of Genes and Different Behavioral Traits.” 

         GEN, 6 Feb. 2019, www.genengnews.com/news/genetics-of-depression-linked-with-  

         hundreds-of-genes-and-different-behavioural-traits/.

First Semi-Identical Twins

According to Science Daily, boy and girl twins have been identified as only the second set of semi-identical or sesquizcgotic twins in the world. They are also the first to be identified by doctors during pregnancy. The mothers ultrasound at six weeks showed a single placenta and positioning of amniotic sacs that indicated that she was expecting identical twins. At 14 weeks these identical twins have showed to be female and male. As most people know, identical female and male twins are not possible. However, in this case, they are.

Doctors state that the mothers egg was fertilized by two of the fathers sperm before dividing. Doctor Gabbett states that in this case, the fertilized egg appears to have equally divided up the three sets of chromosomes into groups of cells which then split into two, creating twins. Some of the cells have the chromosomes from the first sperm, while the remaining cells contain chromosomes from the second sperm, which results in the twins to share only a portion, rather than 100% of the same paternal DNA.
This is the second case which has not taken place since 2007 in United States. Mostly fraternal twins are highly possible for boy and a girl. The doctors are still studying this case, and are hoping for the mother to have a successful pregnancy so this could be further documented. I believe that with this new fertilization, doctors are able to identify, the how and the why of this pregnancy and would be able to procreate this method, since artificial insemination is now highly popular.

Genetic Testing

A women named Katey Bennett was on Facebook one day where she came across a woman named Amanda Dunford in pictures, staring at a face completely identical to her own. Katey later coincidently received a message from Amanda saying they were twin sisters. Amanda was getting a medical procedure done and to get more answers, used genetic testing, which revealed health and ancestry information. When she read the family results it said she shared a 23-out-of-23 chromosome match with someone, therefore revealing she had a twin. With the help of a DNA test the two sisters were reunited for the first time in 33 years since they were adopted by different families. Both sisters were aired on a TV show to go forth with more genetic testing to find one or both of their biological parents. I found this article to be interesting because I also have a sister that I could not live without. For Katey and Amanda it must have felt as if a piece of them was missing. In a matter of fact, for Amanda to be going in for a medical procedure, not even having the intention of finding out she has a twin sister is also incredible and an eye opener for many other reasons. For those who don’t know, genetic testing, also known as DNA testing, is the sequencing of human DNA in order to discover genetic differences, abnormalities, and mutations that may prove pathological. According to the NY Times, genetic testing of embryos has soared and more disease causing genes have been discovered. Although these tests can be expensive, they make it possible for families to ensure that their children will or will not inherit a busted gene. Chapter one in the Genetics textbook by Pierce also discusses how a majority of these discoveries and applications often have significant economic and ethical implications, making the study of Genetics relevant.

https://www.washingtonpost.com/local/virginia-woman-did-dna-test-discovered-she-had-twin-sister/2018/01/12/0949cb52-f7c2-11e7-9af7-a50bc3300042_story.html?utm_term=.ed03163e4ff4



https://www.nytimes.com/2014/02/04/health/ethics-questions-arise-as-genetic-testing-of-embryos-increases.html

Twin study finds genetics affects where children look, shaping mental development

      

        Genetic studies have played a huge role in discovering so many previously-unknown facts and methods in which the human body tends to operate. Recently, a study was done by researchers from Karolinska Institution, (Sweden) in collaboration with, scientists from Indiana University where they tracked the eye-movement of twins. Their goal was to discover whether or not genetics plays a strong role in how people attend to their environment. Unlike most eye-movement studies where the main focus is to find the common features that drive one's attention, Daniel P. Kennedy, (an assistant professor in the IU Bloomington College of Arts and Sciences' Department of Psychological and Brain Sciences) explains that "This study is different. We wanted to understand differences among individuals and whether they are influenced by genetics". 

        In this particular study, the eye-movement of 466 children (233 pairs of twins) was observed. The group was made of 119 pairs of identical twins and 114 pairs of fraternal twins between ages 9 and 14. Each child was given 80 pictures of different scenes that are typical to encounter in day-to-day life and were asked to look at each one. The researchers used eye-trackers to examine general "tendencies of exploration" and to measure the sequence of eye-movement in space and time as each child looked at the scenes. What was discovered 

        After tracking the eye-movements in the twins, a very strong similarity in gaze patterns was found within the sets of identical twins; they tended to look at the same features in the scene in the same order. They also found weaker, yet significant similarities with the fraternal twins. From here, the researchers were able to infer that the common eye-movement patterns in identical twins are likely due to their shared genetic makeup. They also found that with this process, they can reliably identify one twin with their other twin amongst a group of unrelated people; they called this "gaze fingerprinting." 

        This study gives us a new perspective on how biology and environment are integrated into our development. What I find extremely interesting is how it is through the selection process that ends up shaping our visual experiences. However, to take it a step further, it's fascinating to me that where one looks has a huge effect on his/her development. That leaves me wondering if this can lead to similar behaviors and/or experiences amongst identical twins who have been separated at birth. 

https://medicalxpress.com/news/2017-11-twin-genetics-affects-children-mental.html

https://www.news-medical.net/news/20171110/Genes-influence-our-eye-movements-study-shows.aspx

Can Twins Sense Each Other's Pain and Emotion?

         

     According to Dr. Nancy L. Segal in her book, Entwined Lives, she states, “There is no evidence that twins’ similarities are caused by mental communication between them.”  Another Doctor, Dr. Eileen Pearlman said, “There has been no scientific evidence to support ESP in twins.” Although doctors have not found significant evidence scientifically, there are multiple stories of twins that prove this statement might be false. For example, in the article called, I had morning sickness and my twin didn't even know she was pregnant': Meet the identical twins who feel each other's pain, get ill at the same time and can read their sibling's mind, identical twins Angela King and Elena Gatt explained to the rest of us how they could feel each other’s pain – even halfway across the world. One day, Elena fell down a flight of stairs at the Tower of London and injured her leg. Angela, who was thousands of miles away, felt pain in the exact leg at the exact time that her sister did. This is amazing and cannot be made up. These events are what spark scientists minds to try and figure out exactly how twins brains work. Personally, I believe that there is not a connection between twins. Even though twins are born in the same womb at the same time they are still two different people. They do think differently because they are their own person living their own lives. Even though most of the time twins are together during childhood, each twin has their own mind and feelings. But, what makes my decision hard is the personal stories that twins experience. These personal stories are real evidence of twins’ sensing each other’s pain. 

https://www.verywell.com/twin-telepathy-2447130

http://www.dailymail.co.uk/news/article-3090703/I-morning-sickness-twin-didn-t-know-pregnant-Meet-identical-twins-feel-s-pain-ill-time-read-sibling-s-mind.html