T613: Yes, I know, I was just recommending that particular book :). And I wasn’t clear- when I said only a few diseases manifest themselves in carriers, I meant only a few diseases manifest themselves *negatively* in carriers. Many do provide a heterozygous advantage.
DY: Why?
ARWSF: The chances of picking a random guy off the street who has the same carrier status as you is, as you say, somewhat slim. However, if you do marry a guy who, against the odds, IS a carrier, that’s a 25% chance that EACH kid will have the disease.
Rabbi Ekstein founded Dor Yeshorim after four of his kids were niftar from Tay Sachs. They test only for debilitating and life-threatening diseases, and if the odds are really so slim that the guy you want to marry will have the same carrier status as you, then what’s the harm in checking?