Due to the fact that all Assamites are created using the Heartblood, the question arises why would two newly generated  Assamites begin with different generations.

One possible solution is this doesn't happen . Storyteller's allowing Assamite characters could simply set a mandatory generation level for starting characters. If this is the case I would suggest at least 4 dots be purchased in Generation.

However I feel that this penalizes the Character by restricting his/her choice in freebie allocation when other possibilities exist . My  personal explanation is as follows .

As the Heartblood is replenished with the blood of those who have fallen, the strength of the Heartblood can be affected by the severity of the losses to the clan  has suffered before the ghoul is accepted and embraced into the clan .
This has the benefit creating a somewhat stronger new generation of  Fida'i whenever the clan suffers from a setback thus maintaining the strength of the clan.

The generation of a new Assamite is also determine partially  by the generation of his/her sponsor from whom the ghoul in training  feeds from for a period of seven years before the embrace. Having a sponsor  of strong blood seems to allow the body to take full advantage of the Heartblood at the time of embrace.