According to Phlox, both Mettus and his older brother – Phlox's second youngest – never saw "eye-to-eye" with their father and the two had not spoken with Phlox for sometime prior to 2152. (ENT: "A Night in Sickbay")
He rejected his father's attempts to raise him free of prejudice against the Antarans. Mettus unfortunately accepted the views of other influences in his life, choosing instead to embrace the prejudices, creating a rift between him and his father. This caused the two to become estranged for ten years.