In this time, I would like to talk about citizenship.
First of all, I tell you about Japan and Korea. In Japan, from 1985, if you have Japanese mother or father, you can have Japanese citizenship. Also in Korea, if you have Korean father or mother, you can have Korean citizenship. Then can you have dual citizenship entire your life? The answer is NO. You have to choice the only one citizenship when you will be 22 years old.
Next, I would like to tell you about the U.S. The U.S can have dual citizenship. There are many countries that recognize to have two or more citizenship. For example, the U.S., Russia, Canada, Mexico, Brazil, Peru, France, Italy, Nigeria, the South African Republic, Australia, New Zealand, Taiwan, the Philippines, and so on. Because of globalization of recent years, many countries accept dual citizenship.
Is it good to have dual citizenship? From the sight of moral, I think it is good to have dual citizenship because you have two mother countries. But from the sight of logical way, I think you should choice the one citizenship. The reason why I think you should choice the one citizenship is law.
How about military obligation? In Japan, there is no allegiance to go to military obligation, but in Korea, you have to go to military obligation before you will have been 29 years old. If you are a guy, and you have Japanese father and Korean mother, what will you do then? I think it is difficult decision. So, I think you should choice the one citizenship.
Moreover, how about marriage, franchise, and crimes? If you have two citizenships, can you marriage to two people? Can you participate in two countries’ government? If you are a criminal, which country’s law are you tried by a court?
There are big problem about crimes. Even though you are kicked out from one of your mother country, as long as you have two passports, you can enter again with the use of one of the other your passport.
From these reasons, I think it is difficult to have dual citizenships.
by Konomi Yamamoto
JAPANsociology 
I think also it’s difficult to have dual citizenship.We benifit by having individuals with dual citizenship.We can take more than one country the right to freedom and equal rights of citizens and many of the native. We may be able to maintain effective relations with the countries of multiple cultures. However, as you said, there are also many disadvantages. There are complex issues such as citizenship and marriage, divorce, inheritance rights, compulsory military service and so on. So, to have dual citizenship is not easy to undersdand way.
these are sources.
http://www.jca.apc.org/unicefclub/research/96_kokuseki/index.html
http://www.moj.go.jp/MINJI/minji06.html
I was think, if I have two citizenship, I would unable to choose one. However, I knew having two citizenship is big issue from your post.
But if I have two citizenship, that mean I have two race. When I can’t choose one, because one country is my mother county, other one country is my mother country, so choice is very difficult issue.
Two citizenship have political problem, however we should think emotional too.