He studied more than just pea plants I think, but I forgot what else.

Female cats are interesting because, iirc, which X-chromosome inactivation is done in regions rather than individual cells, so you get those grey + white regions, so each region only has one active gene so dominant vs recessive doesn't matter, but its different in the different regions. Not sure if some genes are autosomal that override it though? I feel like it must be given neither of the parents appear mosaic patterned and yet they have offspring with two different solid-colored offspring. Which also means we're seeing gene interactions, not just non-interacting autosomal genes as studied in pea plants (tall/short, wrinkly/smooth, green/yellow).