Life in the UniverseAnswer
How do astronomers find planets around other stars?
Distant worlds can reveal themselves through changes in starlight and the motion of their stars.
THE QUESTION LIBRARY LIFE IN THE UNIVERSE
How can identical twins with the same DNA turn out so different?
THE SHORT ANSWER
Shared DNA does not guarantee identical lives. Conditions before birth, later environments and differences in gene activity can contribute; epigenetics is one part of that picture.
WHERE THE EVIDENCE STANDS
How sure are we?
- Epigenetic marks change DNA’s letter sequence.
- Twin differences must come entirely from environment.
- A family resemblance proves inherited memories or experiences.
Identical twins develop from one fertilized egg and begin with almost the same DNA. Yet their conditions before birth, later environments and gene activity can differ. Shared DNA does not guarantee identical lives.
THE LONG ANSWER
THE LONG ANSWER · ABOUT 2 MINUTES
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Keep asking
How closely related are all humans?
Very closely.
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Sources & further reading
(4)
- Epigenomics Fact Sheet ↗National Human Genome Research Institute
- Monozygous but not identical ↗deCODE genetics (2021)Investigator research report.
- Epigenetic differences arise during the lifetime of monozygotic twins ↗Fraga and colleagues, PNAS 102:10604–10609 (2005)
- A critical view on transgenerational epigenetic inheritance in humans ↗Horsthemke, Nature Communications 9:2973 (2018)Commentary; public university copy.
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CONTINUE THE THREAD
Where this question leads.
Life in the UniverseAnswer
Could a planet without a star support life?
A world with no sunrise could still have internal heat. The question is whether it can keep water liquid and supply usable energy.
Life in the UniverseAnswer
How can humans and chimpanzees share so much DNA and still be so different?
Humans and chimpanzees inherited much of their DNA from a shared ancestor. Similar DNA can produce different bodies when some protein instructions and patterns of gene activity differ.…