Family Proceedings Act 1980, s 57
Yes. The person who is believed to be the father can refuse to have the test, but the court can take their refusal into account when it makes its decision.
If a person refuses to have a DNA test, the court could consider that they are refusing because they are the likely other parent and don’t want it to be proved. If other things point to them being the father, the court can decide that the standard of reasonable proof has been reached and make a Paternity Order anyway.