Monarchies breed inept rulers.

On two levels, depending on the society withchin which the monarchy operates. I’m mostly talking about monarchies of the past, because modern monarchies are more or less a joke.
So:

Level the First: dealing with scenarios where a ruler is monogamous.
Marriages are arranged by a committee of counsellors who have the economic and political well being of the country in mind, and do not consider the personal attributes of either person being married. For example, Queen Elizabeth I was advised to marry a certain Austrian prince. She was, herself, a passionate but very smart person, and she seemed to know herself. At the time she was in her upper twenties. The Austrian guy wasn’t more than 17, and the two rulers didn’t even speak the same language.
The point being that the Queen was very smart in turning him down (or rather, turning Austria down because the poor boy just did what his parents and advisors told him to) because the marriage would have undoubtedly added a level of stress and unhappiness to her life which would have affected her administrational practices. Also, let’s say for the sake of the argument that Austrian boy had a less-than-good-quality mind. The offspring of the King and Queen would have been less capable and fit for ruling than if the Queen had married some really smart un-”noble” person.

*Sidenote*: The term “nobility” is a pet peeve of mine. It is used to refer to the gaudy, petty, greedy ruling class in monarchies. Nothing noble about them. They started off as the knighthood in feudal times, when anyone, including peasants, could become considered noble through their actions. Then as time wore on it became all about family name and connections and the value of the word “noble”, which means of quality or high moral integrity, deteriorated. There was nothing noble about aristocracy. Ok, onwards with actual point....

Level the Second: dealing with scenarios where the ruler is polygamous
This is mostly an issue with Eastern monarchies of the past, but is still seen in... oh shoot.... African nation... oh well, the king has 23 wives or something ridiculous like that.
How can you expect the offspring/future rulers to grow up even remotely normal in a home like that? When the ruler reaches the age at which they gain control of the country, how would they have any idea to manage their subjects who have grown up in an entirely different environment? The ability to relate to the people which they are responsible for and representing is seriously hindered. Also, polygamous rulers often choose their partners based on physical attractiveness, and not their mental capacity or ability to aid with ruling a nation. Thus the offspring are often dumb as nails. Those dumb people then go out and find their pretty but inept partners and the offspring are then *tadaaa!* dumber than nails!
If you take a look at monarchies, often there is a trend of starting off with a really good ruler and then slowly watering down the smartness genes until mediocrity is attained. Then the monarchy is so decayed that either a foreign country takes possession of the nation, or there is a revolution.
This is why democracy ends up working out better. Over time, the weaknesses of one family tree do not affect the good and welfare of an entire country.
But at the same time, I’m not a fan of current democratic practices either. I admit though, in closing that in matters of state and government I am completely and merrily clueless. And I have no actual info to base this off of...

ALSO: my music for the day is the Newsboys. A long time ago, they were cool to me. Then I felt like I grew out of them and just stopped understanding what they stood for. And this weekend I saw the sky and thought of their song "Million Pieces" or "Kissin' your cares goodbye" and it fit my mind and I was happy. Musically they are like soft rock/alternative, but in a very grooving Jack Johnson sense.... I dunno, they just made me smile. :D As did a chance encounter with Chrisss.... wouldn't you just love to know what happened...
Peace