CA is a tough state when it comes to this kind of thing. Since she was married, her husband is the assumed father for any children she has. You can petition the court to establish
paternity, but there is a burden of proof higher than just establishing a genetic connection with the child.
In CA, this burden of proof is as follows (
In re Isaac C.):
"
Under section 7611, subdivision (d), a man who has neither legally married nor attempted to marry the child’s mother may attain presumed father status if he “receives the child into his home and openly holds out the child as his natural child…” The court considers his conduct before and after the child’s birth, including whether he publicly acknowledged paternity, paid pregnancy and birth expenses commensurate with his ability to do so, and promptly took legal action to obtain custody of the child. (Kelsey S., supra, 1 Cal.4th at p. 849.) He must demonstrate a full commitment to his parental responsibilities within a short time after he learned the biological mother was pregnant with his child. (Michael H., supra, 10 Cal.4th at p. 1060.) He must also demonstrate a willingness to assume full custody."
So, after 7 years, it would be extremely difficult for you to meet this burden. Unfortunately, that you didn't know that you had a child doesn't enter into the mix. There have been some efforts to amend the legislation in CA for this, and other reasons. But, as of right now, none have been successful.