Answer: Half of you is exactly as old as your mother. That is because the egg from your mother that was fertilized by your dad's sperm, was present in her ovaries the day she was born.
New sperm, on the other hand, is produced constantly in the male testicles. This process takes around 130 days for sperm to be fully formed, ready to die or create a new life.
So, men manufacture new reproductive chromosome-containing sperm every day, whereas women only manufacture their entire lifelong supply of chromosome-containing eggs once in their existence. This, in fact, already happens before they are born.
Quite enchanting if you think about it, actually.