Originally Posted by Lusankya
Well, other perspectives should be considered as well. Normality, of course, is subjective, but the standard of "normal" is generally what is average, commonplace, etc. By and large, most sexually reproducing organisms are heterosexual; thus, heterosexuality is normal. Homosexuality is a small minority, therefore it is abnormal, or, to use a synonymous term, unusual. For the same reason, large quantities of black people in Japan is unusual, even if there is nothing inherently unusual about having dark skin. I am no expert in this matter of course, and I will defer to your understanding of what is considered normal or abnormal in biology, but the percentage of people self-identifying as homosexual is 4% in the US, and seems to be roughly around that in other Western countries. ADHD, which is considered abnormal, is diagnosed in 9% of American children between 8 to 15%, so going off commonality alone it would seem that homosexuality could conceivably qualify as abnormal (I know that this is not a far assessment as there are other factors involved in considering something abnormal, but it is one piece of the puzzle). I also would like to ask if being genetically abnormal is the same thing as being biologically abnormal, because I would think that as there are things that can be abnormal without having discernible genetic cause (i.e. a person exposed to extreme conditions in childhood could grow abnormally despite being genetically perfect), one cannot simply equate the two.
Hypertension has >50% prevalence rate and does have a significant genetic component to it (which is why we as doctors do routinely ask if your family have histories of stuff like diabetes and hypertension). You cannot define abnormal by just the commonality of the situation as in this case it's something that most of the people in the US have and is definitely abnormal by virtue of the underlying pathology. That is true, yes. ADHD is considered abnormal behaviour because there is an underlying pathology that can be corrected (to a certain extent) via pharmacology and behavioural therapy. We know there is an oversecretion of dopamine in certain parts of the brain that has a major correlation with ADHD and that correcting this oversecretion depresses the symptoms.
Genetic abnormality is in fact different in its assessment from "medical" abnormality in it that genetics tend not to care so much about the phenotypes. Something that is common (rate of >1%) is considered to be wild type whether or not it causes a pathology or not. Of course, the interaction between homosexuality and the environment is still being worked on. We simply have very little understanding of it versus something like Type II diabetes in a genetic sense. And we don't know much about that either.
In the end, I think that the end relation comes from whether or not there is a pathology involved. Homosexuality isn't a pathology as defined by DSM IV, so we cannot use pathology as a standard measurement for homosexuality to classify it as abnormal (or spoken in another way, it is normal according to DSM IV). People have done massive amounts of research on homosexuality and could not find an underlying pathology like ADHD. Everything they have found is within normal limits. It's just that they are attracted to the same gender in much the same way as we are attracted to the opposite sex. That is, the "abnormality" is driven by things like Christianity and people's opinions rather than an underlying pathology, per se.
You may ask about things like pedophilia. I don't have the authority on pedophilia research to make an educated opinion on the matter. There may or may not be a pathology underlying this. Certainly some fetishes (attraction to an inanimate object for sexual stimulation) do have some pathology underlying it due to classical and operant conditioning. It's hard to say if something like pedophilia would be in similar vain or not.