Watch: The parents in this viral video aren't afraid to admit that, sometimes, they simply can't tell their twins apart.

For more than a century, scientists have debated whether intelligence is mostly a product of nature or nurture. Identical ...

There’s a common assumption that intelligence is largely determined by genetics. After all, previously published studies ...

Identical twins who were raised apart may have IQ differences similar to those of total strangers, according to new research.

Twins in ancient Greece and Rome were seen as divine signs or dangerous omens, revealing deep cultural fears about birth, ...