Alex, a human lab rat.

Your Mother (Martha) was a scientist. She had been doing some very experimental experiments before the lockdown. Then Lockdown hit. She had been able to set up a lab in the garage and get her hands on some sophisticated equipment and chemicals. However, the one thing she couldn't get her hands on was any test subjects.

This is where you come in. You were her child. You had volunteered to help her out as a bonding chance and for something to do. It started doing baseline tests including an obstacle course in the garden.

Sitting up in your bed, you groan, as you remember the events of the previous day. Your mother had tested a bunch of experiments using the only available human subject (you, her kid). The first experiment had removed your genitalia, something she wasn't expecting, and in her rush to correct her mistake, she accidentally gave you back both sets. With a large set of tits along with a pretty sizeable cock on top of a beautiful vagina, you decided that you were pretty happy with them, so you asked her not to change you back.

She agreed with only a little protest and moved on to the next experiment. The last experiment didn't do anything, so she sent you to bed, wanting to examine the changes tomorrow. One of those changes had made you shrink, and as you had just started to accept your new situation.