Because of course, Peggy, the girl whose mother put her daughter’s life at risk because she wouldn’t leave her husband. Winds up dying. Without any chance to have any agency or real influence on the larger story. I saw that coming.
But it’s all right, sort of. Because Mom gives birth to replacement babies a year later. Twins! Both boys! No more of this pesky girl stuff in our story, nope.
That’s when the book got thrown across the room.
Add in a healthy dose of disdain for most of the human race, a conviction that stupid people are just stupid and will never learn better, the book’s overall treatment of women (even if that wasn’t unexpected), its general ignorance about non-western countries, and science infodumps that go on a bit too long for the book’s pacing, and my original conviction that Heinlein’s YAs had likely dated badly (based on what I knew of his adult work) and should not be wished on–let alone actively recommended to–contemporary teens stands.
Two things I do give the book credit for: A certain almost-page-turning quality in spite of these flaws. And, the bit about how farming on other terraformed planets begins with growing dirt, even though I knew it did, was pretty cool to think about.
But it wasn’t anywhere near enough. YA SF/fantasy has come a tremendous way since the 50s, when Heinlein wrote this books, and that’s not something to be bemoaned–as some adult genre fans seem to do–but celebrated. YA SF/fantasy today is So Much Better than it used to be, and it’s not a denial of the place older books might have had in our own childhoods to say outright that this is a Good Thing.