In season 12, Penny announces that she does not want to have any children and Leonard reluctantly supports her decision. Later, her old boyfriend Zack and his new wife want Leonard to be a surrogate father to their kid since Zack is infertile. Penny reluctantly agrees to let Leonard donate his sperm. However, when she tries to seduce Leonard despite knowing he has to be abstinent for a few days, her visiting father, Wyatt, points out to Penny that her own actions suggest she is more conflicted over having kids than she lets on, to which she admits she feels bad about letting him and Leonard down if she goes through with never having children. He says that despite her flaws, parenthood is the best thing that ever happened to him and he does not want her to miss out, but he says he will support her no matter what she decides. Leonard eventually changes his mind about donating his sperm, not wanting a child in the world that he cannot raise. In the series finale, Penny reveals to her friends that she is pregnant with Leonard's baby, and she changes her mind about not wanting children.