Missing heritability refers to the fact that genetics has (i)____ find common genetic variants that are associated with complex traits like personality and intelligence. This is surprising because these traits are largely heritable. But if they‘re heritable then, by definition, there must be genes behind that. But with a few minor exceptions, over a decade of studies drew (ii)____. Hence the heritability is missing in our DNA, (iii)____.

Missing heritability implies that the genetic variants of inherited traits cannot be found. Hence failed to is the right choice for the first blank. Also this implies that over a decade of studies drew blanks. And so this heritability which is missing in our DNA is unaccounted for.