I doubt genetic testing for genealogical research and not specifically for a paternal test would be prosecuted. I think if the court found the genealogical test being used for purpose of paternity, then the subject could be prosecuted.
Does FTDNA allow geneologic testing in France? Will they send tests through the mail, and receive samples? If the law was for all genetic testing, then FTDNA would have a policy not to do business with France.
I checked and both FTDNA and 23andMe send kits to France.
Even if those tests are not specifically advertised as paternity tests, a person ordering it would still be prosecuted in France because the law prohibited any research regarding a person's identity through genetic testing. The law does not mention paternity test but "genetic fingerprints". That applies to any DNA test.