Aisha & Dohagirl,
This is a major difference between the Bible and the Qur'an. In the Bible, God's prophets often do things we consider immoral: Moses [Musa] commits murder, Lot [Lut] commits incest, David [Dawood?] commits adultery AND murder. We often see these things as evidence that God's will can be done through even the least likely person. In Islam, to my understanding, the suggestion that prophets would behave so despicably is considered blasphemous.
GIASI,
Have you studied genetics much? The issue you're raising here is the one of penetrance. I'm certainly not an expert on this, but here's what I know. We tend to think of genes as a yes/no proposition: either you got the allele for blue eyes or you didn't. But, in fact, many genes have incomplete penetrance, which means that even if you got the allele for a certain characteristic, it might not ever be expressed. (Type 1 Diabetes is this way. It is clearly genetic and biological -- but if one identical twin has is, there's only a 30% chance the other twin has it. Both twins have the genes for diabetes, but the genes aren't always expressed.) This is actually the case for a lot of genetic diseases and predispositions. It's very rare for the concordance rate between identical twins to be 100% for anything more complex than eye color.
A better way to measure the effects of genes is to compare the concordance rate between identical (monozygotic) twins with the concordance rate between fraternal (dizygotic) twins. Since we assume that twins got similar upbringings, any differences between the concordance rates would tend to indicate the influence of genes. The study along this line that I'm most familiar with is Bailey & Pillard's (1991). According to their study, if a man is gay then his identical twin [identical genes, same upbringing] would have a 52% chance of being gay, his frateral twin [similar genes, same upbringing] a 22% chance, and his adoptive brother [different genes, somewhat similar upbringing] 11%. That shows a significant impact of genes.
So, the short answer: homosexuality definitely seems to have a strong genetic basis, but genes don't tell the whole story. As with any other complex characteristic, environment also plays a vital role. (It's also important to note that "environment" includes the prenatal environment, possibly to a larger extent than the environment after a baby is born. As the APA puts it, "Research suggests that the homosexual orientation is in place very early in the life cycle, possibly even before birth." )
Aisha & Dohagirl,
This is a major difference between the Bible and the Qur'an. In the Bible, God's prophets often do things we consider immoral: Moses [Musa] commits murder, Lot [Lut] commits incest, David [Dawood?] commits adultery AND murder. We often see these things as evidence that God's will can be done through even the least likely person. In Islam, to my understanding, the suggestion that prophets would behave so despicably is considered blasphemous.
GIASI,
Have you studied genetics much? The issue you're raising here is the one of penetrance. I'm certainly not an expert on this, but here's what I know. We tend to think of genes as a yes/no proposition: either you got the allele for blue eyes or you didn't. But, in fact, many genes have incomplete penetrance, which means that even if you got the allele for a certain characteristic, it might not ever be expressed. (Type 1 Diabetes is this way. It is clearly genetic and biological -- but if one identical twin has is, there's only a 30% chance the other twin has it. Both twins have the genes for diabetes, but the genes aren't always expressed.) This is actually the case for a lot of genetic diseases and predispositions. It's very rare for the concordance rate between identical twins to be 100% for anything more complex than eye color.
A better way to measure the effects of genes is to compare the concordance rate between identical (monozygotic) twins with the concordance rate between fraternal (dizygotic) twins. Since we assume that twins got similar upbringings, any differences between the concordance rates would tend to indicate the influence of genes. The study along this line that I'm most familiar with is Bailey & Pillard's (1991). According to their study, if a man is gay then his identical twin [identical genes, same upbringing] would have a 52% chance of being gay, his frateral twin [similar genes, same upbringing] a 22% chance, and his adoptive brother [different genes, somewhat similar upbringing] 11%. That shows a significant impact of genes.
So, the short answer: homosexuality definitely seems to have a strong genetic basis, but genes don't tell the whole story. As with any other complex characteristic, environment also plays a vital role. (It's also important to note that "environment" includes the prenatal environment, possibly to a larger extent than the environment after a baby is born. As the APA puts it, "Research suggests that the homosexual orientation is in place very early in the life cycle, possibly even before birth." )