One of the arguments offered by those in support of homosexuality is that homosexuality is an orientation people are born with and it has the same moral value as the hair color someone has at birth. The implication is that since they are said to be born gay, it is normal and morally acceptable. The media seems to support this idea, and it is a common position held to justify the behavior. But there are two problems with this position.
First of all, there are a plethora of studies with conflicting results and conclusions on both sides of the argument. Nevertheless, we could quickly consider studies that deal with identical twins. If genetics determines sexual orientation, then it should be manifested when studying twins who share the exact same genetic information. However, that isn't the case. Consider this . . .
" . . . If genetic influence were expressed in these data, MZ twins (twins formed from a single fertilized egg that splits into embryos) should have the highest concordance for same-sex erotic preference, and unrelated and half-siblings the lowest. Table 5 is based on pairs in which at least one respondent reports a same-sex romantic attraction (N=527 pairs) . . . there is no evidence for strong genetic influence on same-sex preference in this sample. Among MZ twins, 6.7% are concordant. DZ twin (twins formed from two separate eggs) pairs are 7.2% concordant. Full-siblings are 5.5% concordant. Clearly, the observed concordance rates do not correspond to degrees of genetic similarity. None of the comparisons between MZ twins and others in table 5 are even remotely significant. If same-sex romantic attraction has a genetic component, it is massively overwhelmed by other factors. As argued above, it is more likely that any genetic influence, if present, can only be expressed in specific and circumscribed social structures."