Very funny. Really!!!

    "There are chains of DNA in each spring, protected by hydrogen

bonding...When a person is soaked with water from it, the chains enter
the body and attach themselves to the cellular DNA.  In other words...
when you fell into the spring, you gained the DNA of a woman.  There are
a few other things, but I haven't been able to identify them yet." <<

An interesting piece of research as to how the Cursed Pools function. But that doesn't explain how it can be reversed with hot water. Not to mention that gainning foreign DNA doesn't, _can't_ alter your structure. This is magic. Remember?
Say, what happened to Linna? 
Finally, why Ranma and _Shampoo_?
Let's see the rest of it.