I'm a bit confused by how the genetics list works.

I see there are two columns, and sometimes they will say diferent things. (For instance, one of my pet says both normal bones and light bones, etc.) How is it possible for a pet to have two genes? Is one of them recessive? Can someone explain this to me please?

Thank you!

The gee written in green is the dominant gene, the one in grey is recessive.  Only the dominant gene effects stats.  Every animal gets half it's genes from it's mother and half from its father, thus two sets of genes.