Will fruit/seed of a bonsai yield another bonsai plant/tree? With practice one can create a bonsai; no complicated modification of the DNA in a high-end lab required. The bonsai will even beget bonsai fruit. What I am curious about is - if such bonsai fruit is planted again, will it give rise to a normal, or a bonsai tree?

No, seed from a bonsai tree will not automatically produce another bonsai tree. Bonsai are dwarfed due to restriction of root growth in their small containers - unless the offspring are also grown in environmentally dwarfing conditions, they will tend to grow normally.