ABSTRACT
GeneticsNow let’s take a look at what we know about the genetics of sexual orientation. Questions about the genetics of any human trait can be asked in two ways. One is by what is called population genetics, which means we examine the appearance of the trait across generations of individual families. A more rigorous population genetic technique is to determine the probability of a trait being found in both of monozygotic or identical twins, dizygotic or nonidentical twins (also just siblings), and adoptive siblings. The second method is genetic linkage analysis, which involves examining the DNA of family members to determine if a correlation exists between the appearance of the trait of interest and a unique sequence of DNA at a precise location on a specific chromosome. Finding such a correlation implies that the trait is carried by a gene within or containing the unique DNA sequence. First let us see what population genetics or studies of families can tell us about sexual orientation.
