Oh, that bit about the jaundice in “Three Go...” always immensely irritates me.
For starters, her father is a doctor, not her, you don’t magically inherit medical knowledge. If she’s spent her childhood holidays reading all his medical textbooks it’s not mentioned anywhere.
And then - yawning?????? Insomnia or sleep apnea would be a much more plausible first guess if that’s the only symptom they’re looking at!
Seriously, I’m no doctor, but there must be hundreds of medical conditions which make people feel tired alongside the other symptoms.
If the yawning girl had suddenly also developed a yellow tinge to her skin and the whites of her eyes were yellow, then sure, someone might make an accurate guess about jaundice, but there’s no mention of any actual jaundice specific symptoms!