Believing in our ancestors will definitely betray the truth. This is because our ancestors are not God. They can't tell us the truth. It is only the Almighty God who is the Truth. We cannot get the truth about our life and our destiny without listening to God. God is the truth.
By the way, when we are talking about ancestors, what are we referring to? Is it the spirits of dead men? Is it our forefathers who are dead? Those are demonic spirits deceiving people. Invoking the spirits of our ancestors to have them talk to us about our destinies is devilish.
We are to ask the wisdom of the elderly. The Bible says that the gray heads are wise. There is wisdom is the head of our elderly people. Those are the ones we should seek advice from. We should not think of asking things from diviners. They are not true. They used demonic spirits to speak.
God has given us a Teacher which we are to listen to. He is the Lord Jesus Christ. He is the one that sent from heaven so that we might hear his voice. The voice of Jesus Christ is head in his words. We should read and listen to the doctrines of Jesus Christ and the Word of God from the Bible. That is the truth which we should listen to.