The Sims 4 MOD: CAS Gender Breast Option & Pregnancy Both
Available for download at Mod The Sims
For the nude top to look proper on opposite sex Sims, you need an equippable overlay skin + equippable nude top
I can’t provide those here as they would not be SFW content, but you can definitely find plenty of each online.
A pretty simple mod that allows you to enable or disable breasts for Sims regardless of gender, directly from the CAS Gender Options.
Also includes a slightly edited version of bubbee’s Both Options mod, which lets you make your Sims be able to both impregnate AND be impregnated, from the same menu.
bubbee for their Both Options mod
Made with Sims4Studio & S4PE