Half guy, half girl

Karyn giggled, watching me change. I couldn't see what was going on but I could feel it; the limbs on my side of our body felt lighter and there was a pulling sensation in my waist as it narrowed on my side. There was a tickling sensation spreading down our back from my head and I guessed that meant my hair was growing. My face tingled and I was sure that when I looked in the mirror next a girl would be staring back at me. We rolled over, panting with exhaustion and suddenly my side of the chest started feeling heavier as a breast grew. Fortunately the women in my family were never well endowed so it only grew to an A or B cup. The last change was the weirdest. Our crotch tingled and Karyn's giggles escalated to raucous laughter as she watched. Scared, I reached down with my arm and felt myself. We now had both female and male genitalia - a penis on the left, and a vagina on the right. I had no idea what we looked like down there and had no desire to know. "Thank God," sighed my twin, "You're lucky it's my duplicate that got TGed Karyn!"