There's a well-known, albeit small, chance that you might experience anaphylactic shock, which is indeed a serious concern (hence the 15-minute wait after the jab). You can also suffer anaphylaxis if you're allergic to peanuts and inadvertently consume them. I'm not aware if this condition is hereditary. Apparently, your mother doesn't have this issue. Before receiving a jab, there are questionnaires to complete; perhaps your father could mention it there or consult a physician beforehand.

All the talk about boosters being fatal is the realm of silly conspiracy theories. Like all medications, vaccines have side effects, but the consequences of getting infected are – except, of course, in cases of allergies – potentially far more severe. People do die, and some develop chronic health problems (long Covid) after infection. I recommend trusting modern medical science and consulting a well-educated physician or virologist. Unlike the unqualified practitioners of the past – 'witch doctors' – these professionals genuinely know what they're talking about.