Judicial authentication institutions must have corresponding authentication qualifications, and whether they are reliable mainly depends on whether they have corresponding qualifications. If you go to him and find that he is not qualified, you can ask to see his qualifications. If he doesn't, I suggest you don't do paternity test there, because the appraisal conclusion can't be used as evidence, only the appraisal conclusion issued by a formal appraisal institution can be used as evidence.