twin
Sign in to savethumb|Identical twins can be difficult to visually distinguish especially when young, as demonstrated by brothers Billy and Bobby Mauch. Twins are two offspring produced by the same pregnancy. Twins can be either monozygotic ('identical'), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic ('non-identical' or 'fraternal'), meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell. Since identical twins develop from one zygote, they will share the same sex, while fraternal twins may or may not. In very rare cas
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Twins are two offspring born from the same pregnancy, and they can be either identical (developing from a single egg that splits into two embryos) or fraternal (developing from two separate eggs each fertilized by different sperm). Identical twins share the same sex and genetics, while fraternal twins may be different sexes and share only about half their DNA, similar to regular siblings.
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38 sectionsContents
- <span lang="Indoneaia" dir="ltr">Statistics</span>
- Types and zygosity
- {{anchor|Fraternal|Fraternal twins|Dizygotic|Fraternal (dizygotic) twins}}Dizygotic (fraternal) twins
- {{Anchor|IdenticalTwins|Identical twins|Identical (monozygotic) twins}}Monozygotic (identical) twins<!-- This section is linked from [[Rheumatoid arthritis]] -->
- Mechanism
- Incidence
- Genetic and epigenetic similarity
- Polar body and semi-identical twins
- Degree of separation
- Demographics
- Ethnicity
- Predisposing factors
- Delivery interval
- Complications during pregnancy
- Vanishing twins
- Conjoined twins
- Chimerism
- Parasitic twins
- Partial molar twins
- Miscarried twin
- Low birth weight
- Twin-to-twin transfusion syndrome
- Stillbirths
- Heterotopic pregnancy
- Management of birth
- Human twin studies
- Unusual twinnings
- Bi-paternal twins
- Mixed twins
- Monozygotic twins of different sexes
- {{anchor|Dizygotic (fraternal) twins|Half-identical twins}}Semi-identical (sesquizygotic) twins
- Mirror image twins
- Language development
- Animals
- See also
- References
- Further reading
- External links
thumb|Identical twins can be difficult to visually distinguish especially when young, as demonstrated by brothers Billy and Bobby Mauch. Twins are two offspring produced by the same pregnancy. Twins can be either monozygotic ('identical'), meaning that they develop from one zygote, which splits and forms two embryos, or dizygotic ('non-identical' or 'fraternal'), meaning that each twin develops from a separate egg and each egg is fertilized by its own sperm cell. Since identical twins develop from one zygote, they will share the same sex, while fraternal twins may or may not. In very rare cases, fraternal or (semi-) identical twins can have the same mother and different fathers.
In contrast, a fetus that develops alone in the womb (the much more common case in humans) is a singleton; one of a multiple birth is a multiple. Unrelated look-alikes whose resemblance parallels that of twins are referred to as doppelgänger.