DNA replication errors during cell division cause monozygotic twins to diverge from each other even during the earliest stages of development, a new study finds.

A large twin study in Sweden finds genetics has a much larger influence on the odds of an autism diagnosis, and has remained consistent over time.

A study links having a male twin with women’s educational, financial, and childbearing decisions. Researchers suspect prenatal exposure to testosterone may play a role.

The extremely rare event, thought to be caused by two sperm cells fertilizing the same egg simultaneously, was last reported in 2007.

Now two years old, the Delaney twins were born joined at the head and were successfully separated in June 2017.

He Jiankui says he has successfully used CRISPR-Cas9 to tweak the genes of twins born earlier this month. Some independent experts are dubious.

A pair of calves was born about eight months ago in Tanzania’s Tarangire National Park.

A twin study suggests that the blood-sucking insects are more attracted to people with certain genes.

Twin study shows environmental factors play a greater role than genetic ones in shaping individual immunity.

Analyzing data from a large twin study, researchers have homed in on how host genetics can shape the gut microbiome.

More than school or family environment, a child’s genetics influences high school exam results.

Mice that explore more have higher levels of neurogenesis, suggesting a link between experience, brain plasticity, and the emergence of distinct personalities.

Genetic changes that may initiate childhood leukemia could originate while the baby is still in utero.

Random chance, plus small differences in uterine environments, give rise to divergent epigenetic patterns in identical twins.

Mothers more likely to have twins have heavier, healthier non-twin babies, possibly explaining why twinning evolved.

Controversial new research links autism to the environment, not genetics.