Ok this thought has also been begging me for a while. From what we know that the animals a morpher acquires is stored somewhere in their DNA (That is how the yeerks found the animorphs) Now that would pose a problem wouldn't it? Since their DNA is altered now what if the said morpher had kids? Because half the DNA form two different people equals one offspring. Here are some troublesome scenarios...
Morpher x Non-morpher - the morpher would have technical more DNA than the non-morpher, wouldn't some problems occur here, like a twisted form of down syndrome?
Morpher x Morpher - Now they can both morph and both have more DNA in there systems than they should have naturally, wouldn't this cause problems, one person could have morphs than the others and even if they had the same amount of morphs they could be from different species. That and if they even had the same number of morphs, and they are the same species wouldn't that still cause genetic defects in their children?
Could people inherit morphing from their parents same as hair and eye color, or could they be born with never seen before deformities?
I think it's sort of like..."active" and "inactive" DNA. I mean you have the code in your body for traits that your parents had, but that might not present in you, but it'll show up in YOUR children. And when you're not in morph, the animal DNA is sort of in storage, and it's in a completely different set and completely different coding language than yours. So if you can't mate with it and produce offspring, even if you have it in your system, it wouldn't match up with your human dna I would think, and if you had a child, the human DNA would probably overrule the other stuff, and the body would reject any animal/morph dna there is from your side. Like if you have a heart transplant, you have to be on medication so that your body doesn't attack the heart - even with other human parts, our bodies reject nearly everything, naturally.
But, basically, since the animal dna can't go through the meiosis that human stuff goes through when a successful reproduction occurs, there's nothing in the other person's body that can activate the animal dna to replicate like our human dna does.
Since Andalites don't inherit the morphing ability, I wouldn't think that any other creatures would that were capable of it. It's a technology, and not inherant in our genetic code, even though it can affect what we look like. But the evolutionary basis for it isn't there. I figure it's sort of an add-on to the cells, but it's not in our coding.
If any of that makes sense, I'll be surprised, because I have a massive head-cold and I'm not making sense right now.