Possible Clues:

• Multiply without going forth
• I want to squeeze brother, no other — keep it in the family?
• Select partners from within the family
• Keep close relations?
• Turned out I'd been right to have children within the family
• Keeping it in the family, engender anger when embracing extra education
• Produce or generate within
• I note well, plant has to develop internally
• Mate with close relatives
• Generate from closely related parents