As you said this is really for a different tread....
Well, I see your point prior to the advent of DNA tests. But....
That means mom has to KNOW, rather than have good reason to suspect. Impossible to prove. Even if she tells dad she did that, she is likely just trying to hurt dad, or means she was "pretty" sure. You would be criminalizing adultery really.
For the named father to accept that children are his, he must at least be a contender, right? Considering DNA exists, any father CAN find out for sure. I believe even drug store tests exists (although not court admissible). DNA test has existed long enough now, that a majority of children alive today were conceived within its use.
My problem with time limits are: If dad raised kids for 10 years, never got a test, and suddenly decides to because a divorce is now happening and he wants to get out of
child support? I mean, randomly, some dads are going to find out that kids aren't his. If you think divorce has a cost on society, what do you think the cost is when a 10 year old is rejected by his father??? A whole lot more serial killers I think. You can blame mom, but geez, that's simple biology. When a man cheats, he isn't going to get pregnant. Many a man has hid an affair. When a woman cheats, she might get pregnant. And many woman hide affairs too. They aren't trying to make dad pay child support. They are trying not to get divorced.
That's why I say it is better not to know sometimes.
Also why ancient societies had great penalties for woman who cheat, and very little or no penalties for men who cheat. Because non-biological father may raise child. Respectfully, I think you are proposing a modern equivalent to these practices (actually stonings and such still done in some countries).
In
paternity cases, a DNA test should be done anyway.
He pays child support because he made commitments somewhere along the way. He "de facto" adopted the child as his own, due to his role in child's life as father. Is it after 1 year of raising a child? 5 years? 10 years? We all say that being a "father" is more than biology. Who has made commitment to child? One night stand dad? Or man child has called dad?
Paying back child support? What a mess...