You have a valid point, but you also cannot exclusively say they were not born this way either.
I do not disagree with you about homosexuality being deviant, in the strictess sense of the word - outside of the norm of biological funtion.
Anyway...that is the key point. I believe that is reason enough to not rubber stamp it as equal to heterosexual marriage and make it just an alternative environment for raising children. Those are the issues that matter to me. What kinky thing people do in privacy (consensual and not involving children) is not of interest to me (beyond my right to call it wrong if I want to).
Cause
The disease can be caused by any of a large number of abnormal mutations in a single gene on chromosome number seven. The mutant gene is recessive - it must be inherited from both parents to have a harmful effect. Genetic testing can identify many (but not all) carriers of the gene.
A gene functions by causing the production of a specific protein. A defect in the gene is damaging when it causes a non-functioning protein or no protein at all. In cystic fibrosis the missing or defective protein forms a channel that transports chloride ions and water through cell membranes. The protein is called CFTR (cystic fibrosis transmembrane conductance regulator). Without the channel CFTR provides the normal mucous cells that line the lungs (and nasal passages) cannot take in water and make thick and viscous mucus, clogging passageways. The viscous mucus not only interferes with breathing but provides a welcoming environment for infections, which eventually cause death. Animal experiments suggest that if as many as 10% of the cells in the lining of the pulmonary tract have an effective CFTR gene, the mucus buildup can be stopped.
Incidence
Cystic fibrosis is a relatively common genetic disease. In the United States, up to 2,000 babies are born with the disease each year. It is concentrated among people of northern European heritage, where it affects about 1 individual in every 2,500. About 1 in 25 white Americans is believed to be a carrier of the recessive gene that causes this disease.
Symptoms you are likely to notice
The disease usually shows up in infancy or childhood, but occasionally the symptoms are delayed until adolescence or even adulthood. Typical symptoms are breathlessness, wheezing, and persistent coughing. The affected person may also be constantly hungry, yet underweight. Eventually the ends of the fingers and toes may become broadened, or "clubbed," for lack of enough oxygen.