Cool topic, indeed we’ve barely scratched the surface… 
Prior to OG 1.0 in '99 there were some “proto-overgrow” sites, mostly private, & usenet’s alt.cannabis 
& a lot of information was still private.
So if that’s the starting point(1999) then … Hmm. Most of the old OGers aren’t active or even current members but by 2006 there’d been plenty of sharing & crossing.
In the U S of 'Merica, the Grateful Dead were hugely significant in spreading genetics (albeit randomly through various 'heads) from the 1970s-mid-1990s.
A little earlier but about the same time would be the movement of seeded bud via the surfer scene, hippie trail, “bangkok express”, etc.
And at the same time, we have Neville’s many gifts being born. 
The US-Viet Nam war also brought over some of the early building blocks for what we’re smoking/eating.
But if you want a “menu” or timeline of the homegrown overgrow member creations, start in '99 then stop at '06. 10 year hiatus… 
due to technical difficulties … '16-present would be OG 2.0 stuff.
And consider that some stuff was worked on in parallel by friends of members (AFAIK Vic High wasn’t very active (?) but Subcool was & they shared).
…starting to get in over my head… 
