Why did Juliette's sister did not want to get children? She said she could but
didn't want to give birth. She had adoptive children. At that point she didn't know that her sister's child had become terribly ill and that may have been caused by genetic reasons. So why didn't she want her own children?
Lea didn't know what was going in on the mind of her sister when she did it. I heard women who did this (not for the same reason than Juliette) sometimes just think "they're mine, I give birth to them so I can take them away when I want". So by adopting maybe she tries to avoid this kind of situation.
shareI disagree with this explanation about why Lea didn't want children. I was asking myself the same question, and I do think that she probably felt that her sister was crazy, mentally, maybe based on something her parents had said when Juliette had killed her son. So she probably thought that she also had the same genes, some mad genes, and that she might do the same thing to her birth child (remember she was young at the time too). But I think when she found out the truth, she was really shocked, but should think that maybe it was a good thing she didn't have kids of her own, because it may have been genetics. Or she could realise that it was just a once in a chance sickness Pierre had, and that meant that she could have had her own children all along.
shareWhat is interesting is that Lea's children are both girls in contrast to Juliette's child. At least an adoption gives her an oppotunity to choose the gender of her child(ren).
Lea loves her sister intensely (see how aghast she was about forgetting their café trips after her ballet classes or the diary entries). I can imagine, that Lea wanted to avoid anything reminding her (and Juliette?, though Lea didn't know she would take in her sister) of Juliette's deed (see how upset she was when her little daughter found the picture of Juliette's son), maybe also fearing that it would be otherwise perceived as an accusation by Juliette and she would lose her (again).