Evolution. It is usually discussed over many generations as non-magical creatures have only their DNA to change. Magic, as usual, makes everything more complicated. Why wait several generations when magic can make you better now? Evolution can occur within a single being when magic is involved.
Let's consider the strange case of Harry Potter, for example.
The date is 31 October, 1981. Voldemort, eager to remove any threat to his power, apparates to the small community of Godric's Hollow. After learning of the secret, the Fidelius charm around the Potter home is worthless and the other wards surrounding the property are a joke to one such as Lord Voldemort.
His cold laughter echoes over the property. This is the only warning the Potters have.
"Lily, quickly! Save Harry!" James panics.
As she runs up the stairs, the splinters of the door shower over James as Voldemort calmly steps over the threshold.
"Are you really so ready to meet your death that you don't even want your wand?" Voldemort questions, although he seems uninterested in the answer. A quick 'Avada Kedavra' silences whatever pleas James had.
Panicking, Lily throws all of the furniture in the nursery in front of the door. Maybe it will buy her a few precious seconds.
"Shit!" the realization that she doesn't have her wand is like a punch to the gut.
"Mummy's here, Harry. I'll always love you, don't you ever forget that. You are loved, Harry," she consoles her son in her last few moments of life.
Without a sound, the door and everything behind it crumbles as Voldemort glides through.
"Get out of the way, you filthy mudblood. I'll allow you your life. I only need Harry."
"Never! I'll die before I'll give my boy to you you bastard!"
With that, he cut her down. A killing curse made her death quick and painless. Voldemort glared into the crib. The crib of one destined to have the power to kill him. He would never let that happen.
"Avada Kedavra!" Voldemort shouted in victory. His crowning moment was upon him. As a green light hurdled toward Harry, Voldemort felt joy. He would forever be immortal. No one could touch him.
Until, through a fluke of magic, the curse rebounded. Voldemort's joyful face quickly morphed into one of horror. The curse hit and the shade of Voldemort fled from the house while Harry, wailing for his dead mother, received a lightning bolt scar that would mark him as a famous wizard forever.
Albus Dumbledore was an extremely intelligent person. A century of life experiences tended to do that to a man. He knew that there was every chance that Voldemort would find a way to the protected families. Thus, when he returned to his office in Hogwarts after a dreadful International Confederation of Wizards meeting and the instrument monitoring the Potter home was flashing, he was not surprised. He was saddened by the loss of his former students but he knew what had to be done and he knew it had to be done quickly.
When Rubeus Hagrid approached the Potter home he heard the wails of a broken man. His sobs quickly joined in as he saw James's body in the entryway of the home. He followed the sound of grief to the second floor and into what could only have been the nursery.
There Sirius Black is holding his godson, Harry Potter in his arms. Lily's body is right there, preserved perfectly in death.
"Sirius, I'm so sorry 'bout yer loss. Yeh have to to let me have Harry, though. Dumbledore's orders," Hagrid whispered mournfully.
"You'll protect him?"
"Dumbledore will. He's a great man, yeh know that."
"I trust you Hagrid. Take care of him, I have something to do. I'll lend you my motorcycle." Sirius stood resolutely, ignoring his tears. His task of finding Peter Pettigrew was firmly set.
As he apparated away Hagrid quickly gathered up the bundle that was Harry and set about transporting him to Privet Drive.
It was just after eleven when two pops echoed about Privet Drive. Albus Dumbledore and Minerva McGonagall hurriedly strode up the drive towards number four.
"Are you sure this is a good idea, Albus? I knew the Dursleys. They never were an open-minded bunch."
"Of course Minerva. They are his family. They are the safest place for him and they will love him." Minerva, of course, did not agree but she respected the man too much to question him. When Hagrid arrived and Dumbledore placed Harry on the doorstep of number four with nothing more than a letter she had her misgivings but still she held quiet. She apparated away with a quiet pop soon after the other two had left.
Harry was left alone.
Now most people would consider leaving a one-year old child on a doorstep at night at the end of October an idiotic idea. However, most magical people do not have the same sort of common sense as the muggles do.
Magic, feeling young Harry's distress from the cold, took action. The cold and Harry became one. He would never feel cold again as his core body temperature dropped to nearly freezing.
On that day, Harry James Potter became the world's first ice elemental. He became strong in a way that most wizards would never know. His power over ice and cold would be beyond that of anyone else. He would be able to freeze things with just a touch and he would never know disease, as nearly everything died when it came in contact with him.
Harry had become an extraordinary wizard with the power that Lord Voldemort knew not, and it was only through the simple mistakes of one aged Headmaster. Dumbledore didn't know that his mistakes gave Harry the power to fulfill his destiny.
When Petunia Dursley found the ice-cold child of her sister on her doorstep, she knew that her life had just taken a turn for the bizarre. She hated him for it.
All Harry would know for the beginning of his life was hatred.