So if I, a bisexual man, look at this as a potential dating pool, I see 40 men who might be interested in me... and 485 women who might.
40 times 12 is 480.
Based on simple math, we would statistically *expect* to see bisexuals wind up with same-sex partners about once in *every 13 pairings*.
The fact that we find same-sex partners as often as we do is testament to the fact that we're really, truly looking for them.
(IOW, fuck you, we're not straight or pretending.) 4/4