Yes, a twin can have twins, and in fact, their likelihood of doing so is higher than someone who isn't a twin.
Here's a breakdown:
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Increased Likelihood: Studies show that women who are twins are more likely to give birth to twins themselves.
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Monozygotic Twin Connection: Specifically, if a mother is a monozygotic (identical) twin, her risk of having monozygotic twins increases. One study indicated a significantly increased risk of having twins of the same sex (identical) in this scenario.
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Fraternal Twins (Dizygotic): While identical twins are the result of one fertilized egg splitting, fraternal twins result from multiple eggs being fertilized. The tendency to hyperovulate (release multiple eggs) can be hereditary. If the twin parent is a fraternal twin, they may have inherited the hyperovulation trait, increasing their chance of having fraternal twins.
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Heredity: The tendency to have fraternal twins can run in families. This is linked to genes influencing ovulation. The genes do not, however, increase the chances of identical twins.
In summary, being a twin, especially a fraternal twin, increases the odds of having twins, but it's not a guarantee. The increased likelihood stems from genetic factors influencing ovulation or, in the case of identical twins, a still poorly understood predisposition.
