Anyone can hime right on in 
I would speculate baselessly that evolution has trained us to look for clues that a potential spouse is good genetic material. Without even knowing we are doing it, we check a date’s face for symmetry (very symmetrical faces get women’s pupils to dilate; many elected politicians have more symmetrical faces than average, Bill Clinton was famous for it; ditto for famous actors and actresses). We are turned off by pocked skin, which can mean acne but also once meant parasites. We are grossed out by signs of disease or physical weakness - the halt, the lame, the mentally retarded.
But the system wasn’t designed to pick up all minuscule faults that can show up in the germline, and it was designed to function without words.
So we procreate with a full evolutionary history saying to us “This one looks good, smells good, sounds pretty decent; on top of which, it’s the best one I can get”. And that powerful programming overrides the far more recent intellectual decision to ask a spouse whether they got any nut cases or congenital illnesses in the family, or lurking communicable diseases in the flesh.
Anyway, even a spouse with a medical or family history of a disease that comes on later in life, say Huntinton’s chorea or a strong tendency towards early heart attacks, might be a good bet for children if the kids are likely to procreate successfully before the age of falling over dead.
Is this what you were getting at, or am I totally off the mark?
I would say hardly anyone - and maybe no one - plans their life around procreation with everything else being subordinate to it. Generally planned procreation is in the context of a marriage or similar relationship, where establishing and maintaining a life-partnership is the primary focus. Who’s going to walk away from the love of his life just because her dad had a heart condition, or her mom had breast cancer? Most medical concerns can be managed in some fashion. Finding someone you can be happy with, for perhaps the rest of your life, isn’t as easy.
Because people are more horny than they are logical.
I always investigate the medical history of the spouses I procreate with. If her doctor won’t tell, sometimes her husband will.
Bingo.
I find health history more useful for identifying things to watch out for, rather than things to avoid procreating for. My family is rife with breast cancer. While I’m not going to undergo a double mastectomy to prevent it, I will start getting mamograms in the next year or two (I’m 31) instead of waiting until I’m 40, and I’ll suggest to both my daughter AND my son that they get screened early and often as well (whatever tests there are by the time they’re grown.)
Am I going to deny myself the joys of parenthood and my kids the joys of living because they might get some inherited disease? Probably not for the low to moderate percentage stuff. If it was a certainty - a genetic disease passed down to all my children, guaranteed - and if that disease presented a major shortening or quality of life issue, then I’d probaby consider adopting instead.
Basically, if I had something that made me wish I wasn’t born, I wouldn’t procreate. Short of that, I think it’s important to teach kids that their lives are worth living, even if they aren’t “perfect”.
Well I always checked their teeth. It ultimately did me no good, as all my kids got MY teeth. (Not good.)
On the plus side, all but one got his vision (perfect, like his teeth). And that one got Lasik.
I did actually check. “You never had braces–no, really? Wow. And you don’t secretly wear contacts?” Quite frankly though at that point braces in his past wouldn’t have been a dealbreaker for me, and fortunately wasn’t for him either.
To add to gabriela’s as always excellent post; I believe (and I’m perfectly willing to admit I may be wrong) that when the strategies she pointed out developed, males were likely to (at least attempt) to have children with as large a number of females as possible further increasing the probability that their genes would be passed along.
If a man has children by several women it’s more likely at least one will survive to procreate.
That actually is a small part of why I’ve chosen to not have kids. I only know medical history from my moms side and it isn’t the greatest. Not knowing my dads side at all, I don’t know how many complications might come from that side.