Why Identical Twins Aren’t Truly Identical: Exploring Genetic Differences

Identical twins are created when one fertilized egg divides into two embryos during the early stages of development. These embryos originate from the same set of cells, resulting in virtually identical DNA.

This genetic similarity means they share traits with a strong hereditary component, such as blood type and eye color. However, from that moment, their differences start to grow.

Even though twins share the same womb, their experiences can differ significantly. A minor twist in the umbilical cord, for instance, may lead to one twin receiving a greater share of nutrients than the other.









This nutrient disparity can lead to variations in gene expression patterns, influencing traits like growth, personality, and susceptibility to diseases.

Additionally, differences in intrauterine pressure and positioning can result in identical twins being born with distinct fingerprints. While genetic factors determine the basic fingerprint structure, the amniotic fluid environment shapes its unique characteristics.

After birth, more differences arise. Random genetic mutations can occur in either twin at any time, explaining why identical twins may develop different illnesses, including cancer.

Chance also affects their development; for instance, one twin may contract a virus leading to an autoimmune disease while the other remains unaffected.

Thus, both nature and nurture play crucial roles in their lives. As time passes, their environments will change, further differentiating them.

Even if identical twins grow up in the same household, they often have varied experiences—different teachers, friends, and role models. As adults, they may live in distinct locations, exposed to varying levels of social support, healthcare access, or environmental factors.

All these aspects interact with their DNA, amplifying their differences and ultimately shaping each twin into a unique individual. So, despite being termed identical twins, they are far from being the same.


This article addresses the question posed by Chris Montgomery via email: “How identical are identical twins?”

If you have any questions, feel free to email us at: questions@sciencefocus.com or send us a message facebook, Twitter or Instagram (please include your name and location).

Discover more with our ultimate fun facts and explore our amazing science pages.


Read more:


Source: www.sciencefocus.com

New Study Reveals Dragonflies and Humans Have Identical Red Vision Mechanisms

Recent research from Osaka Metropolitan University has unveiled a groundbreaking visual protein, enabling dragonflies to perceive deep red and near-infrared light. This discovery showcases an evolutionary parallel to human vision, hinting at exciting medical applications.



Asiagomphus melaenopus Female from Miroku Forest, Kasugai City, Aichi Prefecture. Image credit: Alpsdake / CC BY-SA 4.0.

Humans perceive colors through a specific protein called opsin found in our eyes.

In humans, there are three distinct opsins responsible for color perception: blue, green, and red light.

Dragonflies possess notably enhanced red vision compared to most insects.

A recent study led by Professor Mitsumasa Koyanagi at Osaka Metropolitan University identified a unique dragonfly opsin that detects light wavelengths around 720 nm, extending beyond the visible spectrum’s deep red range.

“This is one of the most red-sensitive visual pigments ever found,” stated Professor Akihisa Terakita from Osaka Metropolitan University.

“Dragonflies likely see red light more profoundly than many other insects.”

The researchers posited that this heightened sensitivity assists dragonflies in identifying ideal mates.

To support this hypothesis, they measured the reflectance properties of surfaces, indicating how dragonflies visually perceive one another.

Findings reveal significant differences between male and female Asiatic gomphus melaenopus dragonflies, displaying reflectance from red to near-infrared light. This ability may promote quick differentiation between sexes during flight.

“Interestingly, the mechanism by which dragonfly red opsin detects red light mirrors that of mammals, including humans,” explained Ryu Sato, a graduate student at Osaka Metropolitan University.

“This surprises us and indicates an independent evolutionary development in vastly different species.”

The research team also identified a critical position within the protein that regulates light sensitivity.

By altering this position, they were able to enhance the sensitivity further, enabling the opsin to respond to light approaching the infrared spectrum.

They engineered a protein variant that reacts to even longer wavelengths, demonstrating activation of cells by near-infrared light.

These discoveries hold promise for the field of optogenetics, leveraging light-sensitive proteins to investigate various disease states.

Given that dragonfly opsins are responsive to longer light wavelengths, they could operate effectively in deeper tissue applications.

“In this research, we’ve successfully shifted the sensitivity of the modified near-infrared opsin found in the Odonata family to longer wavelengths, confirming that this opsin triggers cellular responses via near-infrared light,” noted Professor Koyanagi.

“This illustrates the potential of this opsin as an innovative optogenetic tool for deep tissue light detection.”

For further detailed insights, refer to the study published in January 2026 in the journal Cell and Molecular Life Sciences.

_____

Takashi Sato et al. 2026. Dragonfly red opsin shares a common regulatory mechanism with mammalian red opsin, further enhancing near-infrared sensitivity. Cell. Mol. Life Sci. 83, 66; doi: 10.1007/s00018-025-06017-9

Source: www.sci.news