Possible Clues:

• New old man?
• Johnny Cash, to Carlene Carter
• Blended-family parent
• I might show extremes of parenthood in another's place
• Pop from a different line
• Acquired pop
• Parent taking the stairs?
• Edward Murdstone, to David Copperfield
• Jay Pritchett, to Manny, on "Modern Family"
• Non-biological parent