But what about the MZ twins that have a 0% concordance, why are they not statistically significant? If you can't answer this you really have no credible argument.
Taken as a whole, how many studies have found a significant correlation versus studies that have found no correlation? I draw my own conclusions.
And it's merely speculation, but I wouldn't be surprised if any of the studies finding no correlation were somehow funded by Dr. Paul Cameron, Judith Reisman, or some similar person, who is, to put it kindly, less than objective.