OK, so… hypothetically:

Let’s say you’re in your early 40s and all the family members you grew up with are dead or otherwise unavailable for supplying information. You don’t have any idea about whether you’ve ever been vaccinated against $DISEASE or not.

1) how would one find out?
2) is it safe to assume that if you’ve made it 40 years without contracting measles, mumps, diphtheria, pertussis. and tetanus that you can pretty much stop worrying about those things and move on to awaiting your inevitable death from heart disease or cancer? Or does it still make sense at this late state to get those vaccinations?