Born this way, baby

[catfish]

Then how can a set of identical twins develop with one gay and one not???

Experience shows that identical twins are rarely completely the same. Until recently, any differences between twins had largely been attributed to environmental influences (otherwise known as "nurture"), but a recent study contradicts that belief.

Geneticist Carl Bruder of the University of Alabama at Birmingham, and his colleagues closely compared the genomes of 19 sets of adult identical twins. In some cases, one twin's DNA differed from the other's at various points on their genomes. At these sites of genetic divergence, one bore a different number of copies of the same gene, a genetic state called copy number variants.

http://www.scientificamerican.com/articl...-identical

Good read.

The conclussion at the end left me wondering though. What type of evidence would the Bruder report entail that would warrant the bolded assertion?

Bruder speculates that such variation is a natural occurrence that accumulates with age in everyone. "I believe that the genome that you're born with is not the genome that you die with—at least not for all the cells in your body," he says.

Charles Lee, a geneticist at Brigham and Women’s Hospital in Boston, agrees. Genetic variations can arise after a double strand of DNA breaks when exposed to ionizing radiation or carcinogens. "It reminds us to be careful about our environment because our environment can help to change our genome," he says.

Plus, these variations may predict age-related diseases. Lee adds: "As you age … your chances for having a genomic rearrangement that causes a certain disease increases all the time."

The differences between identical twins increase as they age, because environmentally triggered changes accumulate. But twins can also begin their lives with differences, according to Bruder's study, and that calls into question their very name.