The development of bloodline theory was spontaneous and organic. However it's ability to be enforced came from Mao's approval and reaction to the Loyalist Red Guards actions during the cultural revolution. Mao's reform campaigns had a problem that they were so simplified for peasants, that they could be interpreted in various anti-socialist ways. It's a similar problem to the USSR's New Soviet Man and de-kulakization, except like you mention way more grass roots and bottom up. In the USSR you can blame the party's management for "kulak" becoming an abstract label meaning "enemy" however in China the same issue with "bourgeoisie" came more from peasants interpretations of Mao's directives.

However the Party did in fact empower these things. I think the issue with Mao's handling of the cultural revolution was an issue of uniting such a large varied country under a brand new set of principles. The CPC essentially did not know how much would "take".

Chen Boda was the first party leader to actually go against the bloodline theory, and that happened fairly early on in its development AFAIR, like within a year or two.