My response:
Putting aside the potential for criminal law violations, the male and female minors are, and remain, the only persons liable for support, both before and after a live birth. The Grandparents have no liability in this matter for support of a grandchild born to minor children.
Then you ask, if the Grandparents aren't liable for the support of their minor children's child, who is?
Assuming the minor parents are still too young to work, the Custodial Parent (usually the minor mother), will be required, out of necessity, to file for, and obtain, Public Assistance - - such as "Aid to Families With Dependant Children."
In that instance, the Public Agency will Petition the court for orders for reimbursement upon the male and female's age of majority and/or when either takes a job at any age, so that reimbursements, including interest charges, can be deducted from payroll checks. If work is not sought by one or both minors to pay for the Public Assistance, a court will "impute" the ability to earn an income upon the minor children upon their majority - - this will have the effect of "forcing" the minor children to, at least, take a McDonald's type job to start reimbursing the Public Agency (there's more to this part, but it goes too far afield for your question).
Suffice it to say, in California, a parent, like yourself, is only responsible for their minor child's "malicious acts". Sexual encounters between minors (unless the same is forced by one minor upon the other) are not regarded as malicious and, at least in theory, only the minor children are responsible for their offspring - - but that's only "going by the book" - - you and I, along with everyone on this Board knows, all too well, that the reality of such a situation will be very costly for Grandparents due to not wanting to see their grandchild on public assistance, or to have "less" than what you think the child should have. This is only natural.
I certainly hope this helps.
IAAL
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