Well, it's 'luck of the draw' in terms of 'who deserves to suffer from a.n. other genetic flaw' (.i.e. none do, but some are unlucky), but somewhat a matter of probability for any given individual, based on their parent's genetic code (i.e. the probability of me getting sickle cell anemia was almost nil, since my ancestry is exclusively white going back many generations on both sides and it's a disease almost exclusively seen in non-whites). The chances of someone developing, say, Cystic Fibrosis if both parents are carriers are obviously significant. etc.