Description

This video focuses on twin studies and epigenetics, or how embryonic development affects phenotype.  Twins studies show that if one twin is gay then the chances the other twin is gay is dramatically higher, implying a genetic cause.  However, there are identical twins for which one is homosexual and the other is not.  The cause of this is the slightly different environment they were exposed to in the womb and different activation of their genes.

Discussion Questions

• What conflicting evidence do twin studies show?
• What is epigenetics and how does it explain these twin studies?
• What is testosterone and how does it affect our development in the womb?
• How does gene activation affect related individuals?

Keywords: gay, lgbt, evolution, epigenetics, homosexuality, sexual orientation,