User blog comment:Xilinoc/Ch. 542 - THE BLADE IS ME/@comment-10699642-20130619212112/@comment-1938192-20130620174407

Sicarius, genetics don't work like that. Look up 'punnett squares'. Let's say Q represents the Quincy gene, while q represents the non-Quincy gene. Kanae's gene pair is Qq, while Ryūken's is QQ. They could only pass one gene each to Uryu with only two possible combinations, QQ or Qq. Meaning Uryu is either a full Quincy or a half-breed.