Reuniting children with parents

Why has no one suggested using DNA to match parents and children separated by the heinous immigration fiasco we are suffering through. Seems to me that asking parents and children to provide a swab then running it through the same process that these DNA genealogy services use would provide a provable, undeniable match between children and their parents. I read about a GoFundMe page that was started asking for $1,500 to aid these immigrant cases and ended up with over $15,000,000!!! Seems that some of that money could be used for DNA testing, for example. AmIright?