It is complicated in California when it comes to parentage. There are many ways to become a parent that do not involve even being genetically related. Sometimes, if a court order declares someone the father, and time passes, it may be too late for either mother or father to request genetic testing. Sometimes the law may declare someone the legal father despite being a DNA-non-match.
If your ex boyfriend signed the voluntary declaration of paternity and has held himself out to be the father for the past 12 years, he may be deemed to be the natural father of the child. Unless he requests a paternity test or he fights paternity, the voluntary declaration of paternity would be sufficient for Child Support Services.
The response above does not form an attorney-client relationship. This answer may or may not apply to you and should not be relied upon as legal advice.