The problem is, you don’t know what you don’t know. It’s likely that we all unknowingly carry a gene for some sort of recessive genetic condition. Should we all be getting ourselves a full genetic screen before having a baby?
Not to mention that a large percentage of pregnancies are unplanned, as Jesy’s was IIRC.
It’s not really the same thing as knowing you carry a gene for a particular genetic condition, because you actually live with that condition. Of course in that scenario, the sensible thing is to check that your partner doesn’t carry the gene also.