Moral of story:
Please don't design kid faces from scratch. Or at least make sure they look okay as adults too?? Is it really that hard?
There's a reason the toddler to adult challenge is called a challenge.
Why can't the developers just use the genetics feature?
At least then the kids will age up looking similar to their parents.
Also, I'm very curious about what all the kids you folks are mentioning look like when aged up. I haven't really paid close attention, and at this point in my save, most of them are already dead. All I know is that Lucas Munch grew up looking rather meh.
Pretty sure TS3 had this problem too. Bella Goth aged up rather strange-looking there.