The Twelve Kingdoms/Headscratchers

The Twelve Kingdoms

 * If all children in the Twelve Kingdoms are born from ranka trees, how come there are brothels?
 * Apparently sex still exists - even if its unconnected with procreation.
 * Or, heck, marriages? Families even?
 * From the novels, you have to be married for the ranka trees to give you a child.
 * No children born out of wed lock in this world. The ranka trees never made sense to me anyway.
 * Kinda makes you wonder if the trees accept under-age marriages or same-gender marriages. Open, liberal ranka-trees?
 * This is sorta referenced by Rakshun, En, a kingdom with a king who is kind to Kaikaku and Half-Beasts has a higher birth rate of Half-Beasts than other kingdoms. This seems to indicate the philosophical leanings of the king affect the actions of the Ranka trees (Or rather what the king of heaven puts in the egg fruit). So if the king doesn't see anything wrong with legally granting a marriage between a child and adult (Because the king makes the laws and decides what marriages are legal) then in the eyes of heaven (The King is a god after all) the union is also legal and therefore the Ranka trees would bare fruit for them.
 * I agree with most of that, except Rakshun stated that Kou and En have the same number of hanji--its just that the ones in Kou aren't allowed to go out in public in beast form.


 * Does anyone really have any idea when in time the normal-world scenes are set in? It looks like anything between the 90's to the 00's.
 * The 'real world' sections are all set in modern day. That is when the books were published no earlier. In the books Youko makes reference to mobile phones and the Kaikyaku in En was a student in the 1960's student revolution in japan, the fact that he is in his late 30s or so (Based on description) in the books places the series in the mid to late nineties, when Fuyumi Ono started writing Sea of Shadow.
 * But then there's the old, traitorous man who fell into the sea back in 1945, right before the war ended. How old could he have been back then? 20's? 30's? And in the series, he sure doesn't look or act like an 80 year old...
 * But in the books he is described as old, maybe the artist just didn't make him look old enough.