Why can't my Sims engineer a baby in the future?

So I read about this feature that allows same-sex couples to have their own child. Great! Family inventory is empty, they are married, the household is not full, they are good to go. After arriving at Oasis Landing paused the game, clicked on the hospital/science lab, then on 'Create a baby with...' and both randomize DNA and Engineer a baby are grayed out! WTF? So, I bought a new 'Home in the future' for them and nothing. Both options are still grayed out.

Details:

• Both sims are Young Adult females
• they're married
• they live in their own house instead of the Community center (base camp of Oasis Landing)
• their present household contains a young dog, a plumbot Or whatever is its English name) and both Sims. It's still four and not eight no matter how we count it.
• the town's population is way below 180 (i read somewhere about this limit)
• tried with and without mods and CC
• the reason of those options are grayed out because (rough translation) my sim 'doesn't have any friends or doesn't know anyone to do it with' (even though point two)

So my questions are, why can't they do it and what can I do to make them able to do it?