Wrinkle comes under scrutiny when the characters of When You Reach Me discuss it. Specifically, Miranda and Marcus discuss L'Engle's portrayal of time travel. The three Mrs W's promise Meg and the boys that they should be back "five minutes before you left." But as Marcus points out, if this is true then Meg should have seen herself returning, because Meg&co. landed in the garden, which in plain sight from wall, where they left. However, there is an explanation which no one in When You Reach Me notices: Mrs Whatsit says they'll be back five minutes before they left, unless "something goes terribly wrong." And something does indeed go terribly wrong.
In A Wrinkle in Time, Calvin says that he is a "sport" genetically speaking, meaning that he is qualitatively different from the rest of his dysfunctional family of shiftless drunks, bullies, and thugs. Later, on first visiting the Murrys, he states that he feels like he has finally come home. In A Swiftly Tilting Planet, the reader learns that Calvin is not a sport; his nature, including his heroism, comes from his mother's family, the heroic Maddox line. (Indeed, his mother had these traits as a child, but they were beaten out of her, at least figuratively, during the Trauma Conga Line she experienced beginning in her teenage years.) Similarly, there is a reason he feels he has come home upon visiting the Murrys: Again in A Swiftly Tilting Planet it is implied that the Murrys are themselves descended from the similarly heroic Llawcaes — who had repeatedly intermarried with the Maddoxes in the past, given the fact that Meg's father inherited their house, which had been the Llawcae home for generations, as well as Charles Wallace's own blue eyes (in a story where blue eyes play a significant role). Thus, Calvin has indeed come home — to his distant relatives who share his nature.
IT's proxy claims that people are "put to sleep" if they get sick. But this may be only the tip of the iceberg: notice that all the households where the children are bouncing balls in time with one another have kids who are exactly the same age? Guess what may have happened to any siblings who were born out-of-synch with the neighbors'...
Meg's father was actually the second to tesser, he mentions a colleague named Hank who went first. What happened to him?
