1. If their thinking is mature, why not?
2. I don't think so.
3. See question 1 answer.
Question 4: What is the age u started ur 1st relationship?
4. 0 years old. If you mean family relationship, that is. 
If u r a parent, we hope that u can tell us at wad age u started
ur 1st relationship, DO NOT FEEL SHY ABOUT IT! xD
Teenagers dis days started dating about 11 or 12, it's shocking.
Some girls even lost their virginity at the age before 14,
published in the chinese newspaper recently.
Me is not a parent, nothing to answer.
But as a teenager, I do feel that it's shocking. Well, the initial
shock is over. It's like being surprised that kids as young as 7
have a handphone, but that shock is no longer there.
Not so surprising anymore when newspapers keep reporting about
it.