Well, first, heritance of something as complex a phenomena as sexual orientation very likely doesn't depend on a single gene. Many characteristics depend on multiple genes, and it is possible to inherit gradations of a characteristic between extremes. Secondly, there seem to be a number of homosexual couples, especially lesbian couples, that are having kids where one of the members of the couple is homosexual.
None of which is intended to be an argument that homosexuality is inherited; but more to point out that interaction between the chromosomes of two people can, through inheritance of recombinations of groups of genes, cause the descendent of the two genetic sets to have a combined character closer to one extreme or the other than either parent. Thus, your statement neither proves nor disproves "born, not made." Frankly, I don't think the proponents of that statement have proven their case either, but that's another story.
Example, with a very simple gene set. There are multiple genes that control eye color. The gene allele for blue eyes is recessive. Thus, if you have one gene for blue eyes, and one gene for brown eyes, you'll have brown eyes. Yet, if two such brown-eyed people marry and have a child, each can pass their child a blue-eyed gene, and their child will have blue eyes. Take a characteristic that can depend on 5 or 6 genes, and you can see the possiblities.
It would be quite interesting to track the children, both (half-)natural and adopted, and see what their sexual orientations were. I have heard proponents of allowing homosexual couples to adopt children state that such children are no more likely to end up homosexual than the general population is. They offer this as an argument that people who fear that contact between young children and homosexuals would tend to influence such children to adopt a homosexual lifestyle. However, if their perception is true, you'd think that it would also argue against homosexuality being a purely inherited characteristic.
Bologna! There is no such thing as behavioral predisposition, except in the minds of liberal apologists. The practice of perversion has always been a choice, or were incestuals, bestials and pedophiles born that way too?
…There are multiple genes that control eye color. The gene allele for blue eyes is recessive…
But none for behavior! This little correlation is right out of the pro-perversionists talking points, kinda like race and skin color. People don’t choose to be black or white or…and since there are ex-gays; can you please show me an ex-black person? Michael Jackson not withstanding.
Come on Ron, you can do better than this.