Can my sibling give the interview alone?

[iamcougar]

Hi,
My sibling is 15 years old and will be soon applying for a tourist visa and the interview. He is a minor now and my question is will he need a parent/guardian with him to give the interview?

[immihelp]

He can go for interview alone, if he is capable of doing so.

[iamcougar]

Can they ask if he is capable of visiting USA alone? Is there any need to show that he will be visiting relatives?