Do identical twins have the same sexual orientation? if not, does that mean sexual orientation is not encoded in dna?

Twin DNA: Although identical twins have the same DNA, the DNA molecule has the potential for mutation, and changing the gene's expression creating differences depending upon the gene(s) involved. Gender identity is thought to be determined by genetics as well as other factors, although an actual variation or determining factors have not been identified.

No single gene or : biological factor determines homosexuality. As in everything else we are & do, a combo of genetic, epigenetic, biological & environmental factors influence sexual preference. Specific alleles of one gene in a specific pair have been found on the long arms of Chr. 7, 8 as well as the X (from Mom) in male twins who are both gay. Studies show hertability of 31-74% for gay males & 27-76% for lesbians.