One of the greatest misconceptions today about homosexuality is that it is inborn and unchangeable. But there is bullet-proof evidence to the contrary.
It is the simple evidence coming from studies of identical twins, and the more studies are done, the stronger the evidence gets.
Twin studies show if one identical twin is gay, the other twin usually isn't. In fact the identical co-twin of a gay person is gay only about one time in nine. The significance of this is that genes cannot be responsible for sexual orientation. Identical twins have identical genes. They come from a split in a single egg fertilised by a single male sperm cell - not something that usually happens. Usually twins develop from 2 different eggs fertilised by 2 different sperm, and are known as fraternal twins. Although identical twins are genetically the same their sexual orientation is the same only about 10% of the time.
As twin studies of homosexuality continue to be refined and to use larger and larger data bases, what has been called the "genetic" contribution, continues to fall. What is emerging is a picture of individual and personal reactions to life's events - in other words the effect of "environment" rather than "biology". For much more on identical twin studies and what they are saying about homosexuality click on the button below.
Twin studies obviously have huge implications for the on-going debate about the the origins of homosexuality, the malleability of sexual orientation, and the possibilities of change - assisted and naturally occurring.