Before any further discussion of the issues with TEC’s theological document take place, it is important to present the research that TEC missed. Since many churches are struggling with the issue of homosexuality, the information is beneficial to most denominations. It seems quite probable that many churches are not up to date, because they use theological journals to present rigorous science. Although the Anglican Theological Review was interested in the information in this article, for instance, it would not have printed it before the summer of 2009, because of the lag time to publication at theological journals. By then the information would be out of date, and TEC’s error of using old science illustrates the tendency to canonize bibliographies that take a long time to be produced.
One clear area in which recent research has challenged earlier assessments is the genetic causality of homosexual attraction. In 1991 Bailey and Pillard (“A Genetic Study of Male Sexual Orientation,” Archives of General Psychiatry 48) published results of a study in men that suggested a genetic cause of same-sex attraction. It was largely on the basis of that report that To Set Our Hope on Christ concluded that homosexual attractions were based on genetic causes. But a 1994 article called “Homosexuality: The Behavioral Sciences and the Church” by Jones and Workman had already pointed out severe sample bias in that study. Further, a later study co-authored by Bailey did not support the 1991 results.
The 1991 Bailey and Pillard twin study on men looked at identical twins, fraternal twins, siblings that were not twins, and adopted siblings. Seeing traits significantly more often in pairs of identical twins than in the general population suggests heritability of the trait. The authors found that 52% of homosexual identical twins had a homosexual co- twin. Since that was much higher than the 2% rate of homosexuality in the general population at that time, such a large increase would indicate that genetic factors were highly likely. However, the subjects for this study were individuals recruited through gay publications. Besides the obvious problem of who would be likely to respond to such a solicitation, the data itself showed that even the adopted children in the study had five times the normal rate of homosexuality. A high rate in unrelated children indicates that the families of respondents were not typical of the general population. It is clear that the Bailey and Pillard study was subject to sampling bias.
In 1992 King and McDonald (“Homosexuals who are twins: A study of 46 Probands,” British Journal of Psychiatry 160) did a twin study using an unbiased sample. It showed only about 25% of homosexual identical twins had a co-twin who was homosexual. This is still higher than the general population so it could indicate some heritability, but King and McDonald also did something else that any good researcher would do. They looked into the possibility that there might be environmental factors causing even this relatively low rate of concordance. They found that “genetic factors are insufficient explanation of the development of sexual orientation” because of social factors, including “a relatively high likelihood of sexual relations occurring with same sex co-twins at some time, particularly in monozygotic [identical] pairs.” The identical twins were having a strong influence on each other.
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