Looking for my dad
As opening lines go “did you run away from your kid?” is pretty bold. It gets straight to the point and doesn’t leave any room for confusion or misunderstanding. If you’re on the search for your long-lost dad then you probably don’t have much time for small talk.
It does help, however, if you get the right guy first. Otherwise, you end up totally confusing some random person who isn’t actually biologically old enough to be your dad and is then totally confused by your bluntness. Small talk could have helped here.