Not too sure but if it's by genes a recessive alpha might refer to non alpha (N) parents producing an alpha child because they carry recessive genes (a)
eg, his parents are both non alphas but are carries of a recessive alpha gene their kids should either be NN (pure non alpha), Na, Na (non alpha but carries recessive alpha gene) or aa, while is recessive alpha. (if I remember right :P) usually it's Aa, Bb, but using different letters is clearer
for dominant alpha I guess he just got both dominant alpha genes from his parents who are likely pure alphas
It all boils down to the uke alpha is closer to a beta when he is in a group of other dominant alphas but he still ranks higher in a room full of omegas and betas. Also he may handle an omegas heat...that is, he can probably fight his own alpha rutting instincts better than a dom alpha--which is why he can make omegas at the host club feel comfortable. He's a 'safe' alpha.
im sorry, i still confuse about recessive and dominant alpha.. whats the different about them??