How birds become male or female, and occasionally both
- Written by Republished with permission
The highly unusual “semi-identical” Australian twins reported last week are the result of a rare event. It’s thought the brother and sister (who have identical genes from their mother but not their father) developed from an egg fertilised by two different sperm at the same moment.
In humans, it’s the sperm that determines...
Read more: How birds become male or female, and occasionally both