I read in an interview I followed links to that the mother did indeed try to obtain DNA from this man and he has evaded her. She was told by a number of molested children/now adults that he is her son. Time will tell. I think I would have had a private detective obtain DNA or fingerprints on the sly. Hard to do with the man's shaved head and all though.
That was also my understanding; that the man was evasive. Given the weirdness of the claim and his evasiveness, I think the mother has done all we can expect her to do with that angle of her investigation.
I get the sense that she has her doubts about it but doesn't want to ignore the possibility, either.