Exactly. Thank you for making my point!
If non-twin siblings have an orientation correlation of 1 in 20, dizygotic twins have a correlation of 1 in 5 and monozygotic twins have a correlation of 1 in 2, that is statistically significant.
There would seem to be an indisputable, if unknown, biological element involved in sexual orientation.
As there is an equally if not more significant environment element involvled. And being human, it is still ultimately a choice.
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.