Understanding genetic architecture in quantitative traits and complex diseases has been pivotal in biomedical research. Over years of effort and technological advancements, GWASs and sequencing studies have revealed that the genetic architecture of complex traits often comprise of a range of genetic components, including common variant, rare inherited and de novo variants. However, there remains an understudied aspect: the genetic architecture at individuals-level. For instance, individuals in the tails of trait distribution can be predominantly driven by common polygenic variants or by rare/ de novo variants with substantial effects.