Thats jsut wishfull thinkin imo and just a coinsidence.
Isshin and Ichigo ar the first father and son shinigami we have seen, and we have seen thier power aswell, and since a zan comes from ones soul its not so hard to come to the conclusion that the zans are also relatives right?
Its just to bad we dident see Byakuga`s parents, nor his grandfather fight or thier powers, thats just a shame and a waste.
But again Aizen har jack to do with Zangetsu and Engetsu.
镜花水月(kyoka suigetsu) is a 4 character Chinese proverb. The proverb literally translates to 'mirror flower water moon'. Clearly, the flower in the mirror and the moon in the water both are not real but merely reflections. This is apparently to teach peoPle about desires.
The only canon example of a shinigami descended from a shinigami is Byakuya, his grandfather was squad 6 captain during TGTP. No mention of parents, no mention if zan abilities are passed down. Zangetsu and engetsu are definitely connected. They both have already been shown to have GT. Other than having moon in the name I see no connection with Kyoukasuigetsu. The abilities aren't even similar, and illusion type vs. a melee type.
Just what is TGTP ??
Oh and as a side note....Zangetsu, if we transliterate it, it would be more accurate to call it cutter moon rather than moon cutter.....ne