like the anon above me said, stiles could quite possibly cope by researching the fuck outta stuff so he's knowledgeable on the subjects and can sound more in control than he is.

also, like the aforementioned history of circumcision, in-show research montages, and given how quickly he found all that stuff about werewolves, it's kinda safe to say that stiles is the king of wikipedia and does that sort of random search and memorize info things a lot.

as for the personal aspect, stiles is cited as having panic attacks which can feel like the equivalent of an asthma attack/asphyxiation/drowning, however you wanna put it. so knowing someone died feeling the same things he felt on multiple occasions after his mom died probably made it very personal.