Simple solution is to eliminate any parental rights or responsibilities for biological fathers, except those that they have contracted for in writing. As long as states are interfering with personal liberty by involving themselves in regulating and registering marriages (which I hope will stop in my lifetime), a marriage license could be deemed to be such a contract unless there has also been a contract between the parties specifying that the man will not have any or certain parental rights or responsibilities.
Women have 100% control over whether or not they have a baby, and should not be able to decide to have a baby and then foist responsibility for financial support on a man who never agreed to it, even if he is the biological father. And no, having sex doesn't constitute agreeing to shell out money for 18 years. Irresponsible women will keep popping out babies they can't support until society stops treating them like victims after they've done it.
As do men