Perhaps many people are gay and the number of gay geniuses is proportional to the number of gay people per head of population at whatever time they lived.
Also - when 'history' claims that someone was gay they often neglect that that man (or woman in some cases but less) also had sexual relations with members of the opposite sex. Why do we determine that that person was gay and just having hetro relations because it was the norm? I'm thinking Shakespeare as an example here - why can't we just say Shakespeare appears to have been bisexual?
In fact, I would go so far as to say maybe most geniuses are bisexual and only their homosexual relationships are considered interesting enough to go on about. It would make sense to me if most geniuses were actually bisexual because in my own life experience the more intelligent, enlightened people I have met have a higher tendancy to swing both ways - or at very least not to knock something til they've tried it.
I'd agree with that 100%.
After all, why limit your fun to one gender only? Both have lots to offer.
As you say, it's likely that only scandalous stories of sexuality would survive through history. After all, even now, no-one bothers to gossip about the rich and famous who are happily married and faithful to their wives or husbands. No-one wants to hear about that. They're more interested in who's playing around or who's just been outed or whatever and I can't really see humanity having changed that much over the centuries. Gossip and scandal have always been more interesting than the humdrum and far more likely to be remembered whether or not the rumours are true, so I'd always advise a pinch or two of salt when dealing with stories of who was gay or not in the past. There's an old Gaelic preface to gossip which translates as, "If I've been told a lie, I'm telling a lie."
I've just remembered an old Gaelic misogynistic quote attributed to St Columba: "Where there's a cow, you'll find a woman, and where there's a woman you'll find trouble." Maybe that's why he ended up in an abbey which supposedly didn't have any cattle.