re: One step closer to tying homosexuality to the human genome

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I am not following you posts very carefully

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Obviously not. I will try to break this down for you as simply as I can.
A study has been cited in OP that claims there is a specific X linkage seen in brothers who are both homosexual. There are describing a specific locus here, not a random mutation. 808 then asked

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Could the genomes be influenced by the environment and behavior rather than vice versa?

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Which I responded with:

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Can you give me an example of a behavior that reliably leads to a specific re-coding of DNA at a specific place in the genome?

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Highlighted for emphasis. A behavior leading to a consistent mutation at a specific locus. If this exists I am not aware of it, and would love to look at that paper.

Anyways, 808 responded with smoking, which doesn't work at all (I think he thought he caught me in something ) in which I responded with:

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Smoking isn't just a behavior, but a consistent introduction of toxins into the body. It is these toxins that cause endothelial dysfunction and resultant errors in DNA regulation/replication. However, I also said a specific place in the genome, and smoking doesn't cause that as much as it causes global abnormalities.

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Again, highlighted for emphasis. Theres a reason that smoking causes an increase in pretty much all cancers (with a couple exceptions) and that is because it causes global dysregulation. Obviously lung cancer in particular because alveoli and lung parenchyma get a direct hit and higher concentrations than other organs.
Your responses of...

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Researchers sequenced the DNA of tumour samples taken from lung cancer patients to determine the number of mutations present. These sequences were compared to those in normal tissue samples from these patients. More than 23,000 mutations were found in the cancer genome – approximately one for every 15 cigarettes smoked.

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...underlines my point. 1) You have more mutations in the lung because these cells are "hardest hit" by smoke inhalation and 2) these mutations are global and not at a specific locus or chromosome (according to what you posted), and instead numerous at 28,000 and not clustered around a single location.

Thats about as simple as I can break it down. You're in med school, you should be able to follow that.