My eldest started having conversations about pork/bacon/ham = pig, beef = cow, etc between 2-3yrs old. She was somewhat tickled that chicken = chicken... What exactly she was eating came up at most meals and certainly it gave her some pause. There was a moment I thought she was going to declare vegetarianism. However, she was also an avid wildlife documentary watcher, "Walking with Lions" being a particular favorite. She seemed to conclude carnivores eat meat, herbivores eat plants, humans are omnivores and eat both. Certainly we encourage this view, but it was no more than casual discussion on our part...

Her younger sisters have also gone through stages of identifying the connections between food and farmyard, but with less interest (and less interest in animal docos too). My youngest is only just three though, she could yet have an epiphany, which would be unfortunate given her extremely limited food options. The only reason she's growing is her intake of ghee and chicken/meat.

They're certainly concerned with the ethical treatment of animals.