Can you get on child support with out a DNA test??

I know someone who’s on child support and he’s never done a dna test it was from a girl he had a one night stand with out of state he wore a condom also . He still doesn’t even understand how she got his name and social security to file it on him he never gave her any of that and he never did a dna test and he’s on child support and even owes back pay of 8 thousand dollars they were even taking child support out his work checks with out telling him should he get an attorney to get this taken if so what attorney does he need it’s getting worse on him and he’s NEVER MET THIS KID AT ALLL