Asked in Gay Lesbian and Bisexual
Can a person's sexuality be hereditary or is sexuality just a random event that can happen to anyone even if everyone in the family is homosexual or heterosexual?
Scientists do not currently have a clear answer to this. In 1991 and 1993, Bailey and Pillard found that there is a high correlation in identical twins having the same sexuality. 52% of homosexual twins were both homosexual. When you consider that only about 10% of the population is homosexual, it is a near statistic impossibility for there not to be some genetics involved.
This shows that there is definitely some genetic involvement, but we do not know that if it is a genetic predisposition combined with some early childhood event that causes this, or if some homosexuals are definitely homosexual based on their genes while others have their sexuality form as a part of early childhood in the same way that other personality traits are formed in early childhood.
Unfortunately, we don't yet know what causes homosexuality exactly or for certain, though most scientists believe that it is some combination of genetics (heredity) and early childhood development.
The evangelical who answered this before stated that homosexuality is a choice. This is absolutely false, but what he may have meant to write was that though sexual preference is not chosen, people may choose the behavior they will engage in. A common Christian position on this is that many people face temptations to sin. This may be with heterosexuals who wish to commit adultery, drink to excess, or who fail to show people the love and generosity that Jesus commanded us to show one another. All of these temptations to sin should be resisted.
Answer edited to remove speculation, studies that are not cited, and discussion.