Why would heir being homosexual make you quit? Hell, whenever I use ruler designer I -always- start as homosexual. The disadvantages are incredibly minor.
Also, I almost always quit because I've welded together half a dozen kingdoms and there is absolutely no challenge left.
For example, I once quit when I had conquered all of Iberia and France and hijacked the Caliphate. At that point I launched a Crusade against Mauritania then Africa then Sicily. Got tedious.
Another time I played as Duke of Kiev, converted to Catholicism, conquered all of Rus, most of Khazaria, and when the Golden Horde showed up, I swore fealty, raised my heir Mongol Catholic, took over the Horde, and then pressed a tribal Invasion on Poland and seized every single title and replaced them with Mongol Catholics. At that point the only thing left to do was keep pressing invasions and moving on.
Another time I quit after I unified the HRE and the Shia Caliphate.
Each time I started as a Duke or a Count. You spend the first few decades getting into position, then a few more pulling off something ridiculous, then a few more proving you can hold it together, then it's 1250 and there's nothing left to do.
