From your comment 117548 I get the idea that you believe in the influence of parental relations on a child’s future sexual orientation and/or behaviour.
“Personal history and home environment will have an effect on gradient of attraction. Family stability/instability has a proven effect on behavior, and good or bad choices of response to attracting stimuli, including relationships.”
The Langstrom et al study points to 0 shared environmental influence on twins’ same-sex sexual behaviour. You can, at most, claim that somehow parental influence gets into different treatment of each twin or different response of each twin to similar parenting (with one twin being more vulnerable to a particular parental approach). But you would have to produce some empirical evidence for that.

A twin can at will either choose to emulate his brother, or go in a different direction to express his individuality, while interacting with his home environment. One might choose to regularly read Popular Mechanics, and the other Playboy. This choice will set different directions for behavior, as well as values and convictions. The free will factor cannot be discounted or eclipsed by congenital or environmental conditions.

“We’ve looked for common variants in schizophrenia and get almost nothing,” said Dr. David Goldstein, a geneticist at Duke University and one of Dr. Stefansson’s co-authors. “This means natural selection has done a really good job of purging them away, and we’re left with rare variants, a constant flow of them, as the principal driver of the disease.”

The search for common variants in schizophrenia, however, has not been very successful so far, though not for want of trying. There have been more than a thousand studies, implicating 3,608 genetic variants.
But when all the data are pooled, only 24 of those variants turn out to be statistically significant, according to an analysis in the current issue of Nature Genetics by a group led by Dr. Lars Bertram of Massachusetts General Hospital.

One last note, if you read the story one scientist theorizes that since common genes don’t lead to Schiz it must be caused by thousands of rare mutations. Guess what? WRONG! Mutation isn’t nearly common enough to give 1% of the population a mental disorder. Schiz is triggered by environmental damage and he knows it. He’s trying to protect the funding for his his gene research.