Samuel led Israel as an honest judge. His sons, we are told, did not follow his example, which led to Israel's demand for a king. (That makes no sense to me. The hereditary line of a judge is inadequate, so the people want to set up another hereditary line on the assumption it will turn out better? What's the definition of insanity again?) Samuel's mentor, Eli, also had terrible sons, so maybe Samuel's failings as a father came from poor modeling.
One book later, we read about King David's troubles with his offspring. Those issues follow the Davidic line until the split into Israel and Judah and afterwards.
If you go way back to the Patriarchs, you'll see all manner of poor fathering. Abraham tries to kill his son (okay, that doesn't count because God told him to, but you have to wonder what Isaac thought about it as he grew up). Isaac plays favorites with his boys, and the favoritism continues and expands with Jacob to the point that his favorite son, Joseph, gets two tribes -Ephraim and Manasseh- by the time they take the Promised Land.
The Bible often records history without moral commentary. For example, His design for marriage appears to be one man and one woman (Adam and Eve). Were polygamy acceptable, you would think He would have made several women. However, most of the OT folks had multiple wives and no judgment (other than the natural consequences of jealousy, bickering and unrest) seems to fall on those families.
Many times, it is the writers of the New Testament who provide the interpretation of God's opinion on some of the things flawed people did. Perhaps those insights were passed down verbally or given to the Apostles specifically as special revelation. I'm grateful for them. I have trouble understanding why people do the things they do when they obviously know better.
The Apostle Paul encourages the church to choose men whose children are God-fearing to be elders and deacons. Is this to provide examples of good boundaries? Is it that fathers with non-God-fearing children cannot lead effectively? Or should those fathers perhaps channel their energies into dealing with their own planks before helping others with that speck of sawdust?
So, while God used many men as powerful leaders, I suspect it is His intention for more of them to be leaders within their families, as well. It is a far harder job, but eternally rewarding.