And it's not only same-species. Remember when Marco was doing it by accident?
Yeah, but those were completely random. and none of them were useful. In fact KA used this as an answer to why the animorphs don't mix morphs. Because you end up with a bunch of useless parts. like a lobster out of water, or an osprey that needs to be in water to survive.
ax's human morph doesn't count. you're not mixing animals. You're mixing humans. It's almost like giving birth to a human. DNA from two humans. you get some from each parent and you create a new human. Mixing animal DNA, would be like two different animals mating. Hmm...I wonder if the animorphs could use the frolis maneuver to combine lion and tiger dna into a liger?
strangely, I once found some animrophs books in the fantasy section...