Translation guide
In Japanese, the word for twins depends on whether they are identical or fraternal, and there are also specific terms for twin siblings. The most common and general term is 双子.
Referring to two children born at the same time, without specifying type.
The most common and general word for twins. Can be used for both identical and fraternal twins, though it often implies fraternal twins in medical contexts.
She is pregnant with twins.
Those twins look very alike.
A more formal or medical term for twins. Often used in written contexts.
Twin studies have contributed to genetics.
Twins that developed from a single fertilized egg and look exactly alike.
Twins that developed from two separate eggs and may not look alike.
Referring to one person who is a twin.
双子 is the everyday word for twins. 双生児 is more formal and often used in medical or academic contexts. In casual conversation, 双子 is always preferred.
When referring to your own twin sibling, use the appropriate family term: 兄 (older brother), 弟 (younger brother), 姉 (older sister), 妹 (younger sister) with 双子の. For example, 双子の妹 means 'my younger twin sister'.
Identical twins have the same DNA.
Fraternal twins can be of different sexes.
My twin brother lives in Tokyo.