I told him, "If I count up all the sims in my Neighbourhood, I'm sure less than 10% of them are gay." He said, "OK, just count the ones you play." This turns out to be 37 straight, 18 gay or bi and 14 unknown (shy adults who've not met the right Member(s) Of The Appropriate Sex(es) yet, or children too young to have romantic relationships).
So I said, "OK, now let's count up all the people we know who are straight." Immediately, we could think of... 9 people, who are all heterosexual, although some of them are poly or kinky or furry with their heterosexuality, which imo discounts them from being "straight". A bit more thought has got me up to 20, but that involves friends-of-friends (e.g. kshandra's husband) and assumptions about people we know based on the fact we've only ever seen them partnered with Members Of The Opposite Sex, not that that proves anything. (This is particularly difficult for the few people we know who have been monogamous with the same partner for all the time we've known them - how am I supposed to know if they're straight or not? I only know about the partner they're with!).
In contrast, it's very easy for me to think of over 100 people I know who are bisexual: almost everyone at a BiCon, except the handful of heterosexual or gay partners, and further handful of asexuals! and 5 or 10 people I know who are gay. If I included birth family in the numbers, that would weigh it back towards heterosexuality, but only because I have over 30 first cousins, most of whom are married to MOTOS with children. Nonetheless, at least 3 of my first cousins are gay or bi (some of the rest are probably closeted, or out but I haven't spoken to them in 10 years to know). And I think, even including my extremely extensive birth family plus Richard's tiny family, the number of non-straight people I know from BiCon or #soc.bi or alt.poly would still make the people I know in real life 50% straight:50% gay or bisexual.
My sims are on 53.6% straight, 26% gay/bi and 20.3% unknown. Even if all the "unknowns" turn out to be queer (which I doubt - at least 1, I think, is asexual), that's still around 50:50. My sim world accurately represents my real world - in this, at least.