I'm reading the 2010 Superman family comics, and the story I'm reading currently touches on Brainiac 5's family history. It starts with the modern day Superman villain, Braniac, and ends 1000 years in the future with Braniac 5. Something that's not made clear is what the timescales are for 2 of the Braniacs. It's clear that Braniac is in the present 20th/21st century. Braniac 4 was Braniac 5's father, so they're both 1000 years in the future. But Braniac 2 and 3, did they both live 200-300 years? Do Coluans live that long? I'm curious how after 1000 years have passed, there have been only 5 Braniacs.
The New DC 52
DC's New 52 timeline has not been established for Brainiac 5 or his lineage. If changes have been made from the previous iterations of the characters no information has been confirmed.
Pre-Crisis Brainiac 5
In the earlier versions of the character, Brainiac 5 is from the planet Colu (also called Yod) and is the descendant of Vril Dox, an organic slave in service to the Computer Tyrants who ruled Colu. Once they were machines in service to the Coluans, somehow they rebelled and took over the planet. During their time in control, they created Brainiac I who became the enemy of Pre-Crisis Superman. Brainiac I was created to appear human and spy on humanity throughout the galaxy.
The organic servant to Brainiac I was a Colu native named Vril Dox, who had been brainwashed into believing he was descended from Brainac I and was called Brainiac II. Vril Dox, in a bid to escape the Computer Tyrants, created and exposed himself to his "brain stimulator" which increased his intellect to the equal of his robotic masters. He then led a successful rebellion against them.
Coluan live a lifespan far in excess of baseline humans, likely a byproduct of genetic engineering on their part or on the part of the Computer Tyrants. Vril Dox married and eventually gave birth to his son Pran Dox. He discovered his genetics were affected by the brain stimulator and passed the increased intellect to his descendants. His son Pran Dox, was nicknamed Brainiac 3. He, in turn, was the father of Kajz Dox (Brainiac 4), whose son, Querl Dox, became Brainiac 5 of the Legion of Super-Heroes.
It would appear, the average Coluan must live in excess of at least 225 years of age and be able to bear children well into their later years for 1000 years to have passed and to have only had three successive generations, from Vril Dox to Querl Dox.
Post-Crisis versions of Brainiac rarely deviated much from the established character history making only cosmetic changes to the base story. The history of the Legion as a whole however, is so twisted with time travel to parallel worlds it is very difficult to determine how much of the information for the Legion and its members remains accurate since their creation in the 1960's.