Nobody comes from a ‘long line of vegans’ either.

Ruminants with fermentative digestive systems (and animals like rabbits that eat their own feces) can produce B12 - but only if we supplement their feed with cobalt. Though We end up adding b12 to their regular feed as it’s essentially advantageous for their commodification. Omnivorous animals like pigs and chickens require b12 supplementation much the same way vegans take it. The only difference between me and you is I don’t bother slaughtering a sentient life to take my multivitamin.