Duke of Canterlot

How to become an alicorn User's guide

feel free to give some theorieson the topic

personally I am going with the theory  that an alicorn is just a combination of all three pony types/tribes's magic trough a magical or special genetic process or spell ,

example 

Twilight could have gotten the powers or esents of her friends when she completed Starsworl's spell 

giving her enough magic of the three pony types to transform. 

(credit to Sawtoothwaves for the original base of this part of my theory )

a similar thing might have happened with Cadence, like maybe she absorbed the magic of the 3 types through the sharing of love  somehow 

and as for Flurryheart vs the Cake twins, Flurry had the dna sequence for the alicorn genes from Cadence's transformation

but the cakes although they have dna from all 3 types of pony , they don't have the genes or magical spell or process to combine it , but I am sure that if Zecora and Twilight were to study this they maybe able to make a potion or spell that can turn a pony into an alicorn, but it may only work on ponis that have all three pony dna types

as for gen 5 , they show it in a much simpler way  with Sunny and the three artifacts