Where are you from?

Cò às a tha sibh?

Here is how to ask someone where they are from.

Cò às a tha thu?
Where are you from? 

Use   thu  when you speak to a child or friend.

Cò às a tha sibh?
Where are you from?

Use  sibh  to talk to someone older than you, someone in authority, a stranger or more than one person.