Sarah becomes Dad.

Then, Sarah put dad's old clothes on, and when she was done, her face became less blank and more animated. But something was changing. At first, her clothes were baggy and she needed some smaller stuff (several measures), but not now.
In fact, her body inflated quickly, just filling perfectly the clothes Mikey gave her.
Then, her hair shortened and darkened, with several sings of grayness.
Her facial features hardened, then some stubble grew in her face in a clear male pattern, and soon she sported a thick moustache like Jon's dad did years ago, before his sudden death.
Sarah/dad smiled to Mickey, and said in a booming voice:
"Now I know who I am, dear son.. thank you."
Mikey watched stunned the change that occurred before his eyes, and was unable to speak.