Posted: May 06, 2016 4:05 pm
by Keep It Real
In 2000 Bailey, Dunne and Martin studied a larger sample of 4,901 Australian twins but reported less than half the level of concordance.[5] They found 20% concordance in the male identical or MZ twins and 24% concordance for the female identical or MZ twins. Self reported zygosity, sexual attraction, fantasy and behaviours were assessed by questionnaire and zygosity was serologically checked when in doubt.


https://en.wikipedia.org/wiki/Biology_and_sexual_orientation

http://psycnet.apa.org/journals/psp/78/3/524/ - Abstract.