Point one is that the man you've called 'dad', isn't worth knowing, to have dropped your paternity on you in that way. Second point. He's not that worried about finding out or of course he'd pay for the test. So do with it what you will. Simplest solution? Ask your mum if therre"s any chance your dad could be right, and if, based on that, you feel you need to know, you then decide whether it's worth the expense of trying to find out. Please remember though that you can only discount your 'dad' as your father through a paternity test. You'd need another to discover who your real dad is. Personally I'd just be getting on with my life which is what matters. Not your biological father.