Originally Posted by Drobium

The DNA won't have weakened as each cutting is genetically identical to the mother plant.
The problems may arise from the growing conditions of the plant.
Firstly, change the feed from miracle grow to tomato food, miracle grow is way too high in nitrogen, which will just encourage lush leaf growth, you need potassium for flowers.
And feed them once every 10-14 days in the growing season.

Also what soil do you use? multi-purpose over the last few years has slowly been getting lower and lower quality, this is due to the EU saying that we have to reduce peat by 30% or something.
Buzzies love a very peaty compost and have not been doing well at all in the new 'eco' friendly stuff.
So try to seek out any brands of compost that are still mainly peat based like Levington or Petersfield.
Avoid Arthur Bower's at all costs, that stuff is dreadful atm!

Also increase the light levels a bit and put some of the cuttings outside for the summer in dappled shade or sun for a short while.

Buzzies LOVE water and so long as they are not overpotted, it will be very difficult to overwater them and they'll repay you with lots of nice flowery growth!

Hope this helps?