Both Jesus and his Jewish audience in this passage were well aware of the Pentateuch's commands to filial piety. This is not a contradiction in Jesus teaching, but rather a paradox.

The entire book of Luke, from the first chapter where the author lingers over the story of Elizabeth and Mary, is conerned with family life. Looking back to the first chapter, one may see how Jesus' words are perhaps consistent with a notion of a God that loves families and family life, but will not allow Himself to be bound exclusively to the rules of family life. See in particular Jesus' words to Mary after he was found in the synagogue.

Jesus wants us to love our fathers, mothers, wives, husbands, children, brothers, and sisters -- but not more than we love God.

See also Matthew 12.50 where he tells a crowd that whoever does the will of his father is his brother and sister and mother.