No. A lot of people have tried putting a teenage son and daughter in the same room, and the result is almost always the same: They have sex.
If the twins are the same sex than no they can share a room as long as they would like. However if it is a boy and girl yes they need their own rooms now.
Well, the boy is one person, and the girl is another person, so that's 2 people=2 rooms. Three rooms if you include you and perhaps your wife.
Yes it is not deemed necessary to have separate rooms until one of them starts puberty.
No, there is no law stating that any children must have their own rooms. Although if the children are about 8 - 10 years old or older, I would put the two girls in one room, and the two boys in another. If they are younger than that, then I see no problem with any of them sharing a room.
OF course.
You could do an ocean or beach theme. Fish, water, sand, sun, ect.
Yes, as long as it is the boy's fitting room and not the girl's fitting room.
no
good
the date in which the girl and the boy started dating.
Yes until the girl gets pregnant then she will start fighting the boy so you will have to get him his own cage.
The Girl Scouts and Girl Guides share the same motto as the Boy Scouts. This motto from 1907 is 'Be Prepared."