There are some genetic morphs that can create issues health wise if mixed. I know the spiderx spider cross has been discussed but not confirmed? There are a couple others but I can't recall them off the top of my head.
How about rather than just tell this guy to "educate" himself, some on offer up the necessary info or provide a link to it? No need to over complicate this. Forums are meant for helping others imo, let's try to do that.