More than two years into their marriage, the King and Queen have long stopped being chaste with one another, but conversations about offspring remain awkward in their household. The Queen knows that Doctrine describes continuing the family line as a marital duties, and she knows all their advisors expect them to produce heirs. Sometimes she even wonders what it would like rear an infant; if the literature is correct and she'd instantly be overwhelmed with maternal love she had hitherto never held. However, when she broaches the subject with her husband, all she gets are nervous fidgeting and noncommittal answers. And as her desire for children isn't that strong, she's happy to let the question lie dormant for another few months.
But when her handmaidens and inspectors bring in the latest court gossip, she has to discuss matters with her husband. This times she's blunt in a way he can appreciate.
She asks him if his reluctance to bear an heir is because he has nephews. Or rather, he has sisters-in-law who have plans for his nephews, and fears over what the Queen might do to these same nephews. The king admits his relatives have expressed their fears to him, but he trusts his Queen to be kind to these innocent boys, if only because he considers them family. He doesn't care about who the next king is, so long as they take good care of the kingdom. He believes several of his nephews could, but he also knows that a child raised by his queen would be unstoppable; he's just unsure if he's capable himself of being a father, and doesn't want to put yet another thing all on her
The Queen is both touched and embarrassed. She hugs him and tells him that she's seen him with his nephews, and she knows he would be a wonderful father. The King smiles, but has one last question.
"What if they turn out like me?"
She kisses his forehead. "That would be wonderful. Imagine them, as brilliant and compassionate as their father.."
"...and as brave and impartial as their mother."
They still adopt some of the little rapscallions that come into their danger-fraught lives though, whether out of a debt to their tragically deceased parents, or because they bonded with the child.
(Thanks to @spiralcass for helping me with this concept)