Even those who haven't had good fathers or haven't been loved well by human beings have an idea of what a good father is like & have an idea of what love is like. Every person knows what true love is despite the fact that they may have some false ideas mixed in with it.
How do I know this? Because the unloved & those with bad fathers say, "he should have done this.. he should have done that.." & they are right. This is why Jesus said, "treat people the same way you want them to treat you." Even if you've never received or given true love everyone has a decent idea about what it is & everyone longs to receive it & ultimately to give it as well. We are made in the image of God & God is love. Humans aren't inherently bad, we are inherently love. There are just falsehoods in an imperfect world that keep us from being that love. This is why God doesn't erase your personality when you are reborn. He makes you into a new creation while leaving you as the same person. He sanctifies us, which literally means He purifies us. You can't purify something if there was nothing good there to begin with.
Just as orphans & adopted children long to know their biological parents, people search for love & long to know it. Every search for love is a search for God because God is love. Think about that for a while.