Fraternal twins are known as which term?

Delve into the IB Psychology Biological Approach. Practice with multiple choice questions, each offering detailed explanations. Enhance your knowledge and boost your readiness for the exam!

Multiple Choice

Fraternal twins are known as which term?

Explanation:
Fraternal twins form from two separate eggs fertilized by two separate sperm, so they develop as two distinct zygotes. That genetic setup makes them about as similar as regular siblings—roughly 50% on average—and they can be the same or different sexes and often look different. The term dizygotic literally means two zygotes. By contrast, identical twins come from a single zygote that splits, which is why they’re monozygotic and genetically nearly identical. Conjoined twins result from incomplete separation of the zygote. So the fraternal-twin label is dizygotic.

Fraternal twins form from two separate eggs fertilized by two separate sperm, so they develop as two distinct zygotes. That genetic setup makes them about as similar as regular siblings—roughly 50% on average—and they can be the same or different sexes and often look different. The term dizygotic literally means two zygotes. By contrast, identical twins come from a single zygote that splits, which is why they’re monozygotic and genetically nearly identical. Conjoined twins result from incomplete separation of the zygote. So the fraternal-twin label is dizygotic.

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