What further premise is needed in the sibling-emancipation example?

Argument Without New Proof: Absence of a Cause and Presumption of Continuity

• Treating the kinship rule as dependent on analogy while ignoring possible texts
• Proof of exclusivity of parenthood or investigation of alternative causes
• Proof that kinship and parenthood are identical in all cases
• Evidence about the time of ownership rather than the cause of emancipation