From the point of countries, politicians will perceive the ongoing situation as a wake-up call with regard to lower birth rates, more demands on houses, and more energy consumption. Firstly, more single households mean more single persons, and the population will shrink in the wake of falling number of married couples. Secondly, more houses are required to fulfill the need of individuals, which cause cities even more densely populated. London is a famous example; the number of houses has been stimulated by 48% over the past five years, and 80% of them are for singles. Finally, the consumption of electricity and gas will soar when more people choose to live on their own, and it will further pose a threat to our livelihood.
• The insufficient knowledge on the topic. Sometimes, the issue seems to be very simple and well-known to the professor but, in fact, is not familiar to some students, especially, in the first year of the university or college.
• Too much knowledge and ideas on the topic. Throwing away your thoughts to reduce the word count to 500 is often a very challenging task.
• Formatting. If you have cited several sources, it might take time and efforts to put them all in the correct format and alphabetize them.
• Accurate English grammar and punctuation. It is evident that ill-spelled paper can’t make a good impression even if the content is excellent.
The taboo seems to have lifted for second cousins. Notes in "Of Maeglin" in the Silmarillion imply that this twist of Maeglin's was part of the curse of Mandos upon the Noldor. Notes in Morgoth's Ring imply that, if you were first cousins but your uncle was your father's half-brother, this abrogated the incest taboo enough that marriage was an option. Further notes to LACE, strangely following the footnotes (page 234 in my copy) discuss other incest-taboo overlap possibilities that beautiful immortals have to worry about. "None of the Eldar married those in direct line of descent, nor children of the same parents, nor the sister or brother of either of their parents; nor did they wed half-sisters or half-brothers." (LACE)