But this time we're going to colonize, it should be more or at least more than "normal" females and children of the species that make the trip, for what it seems there isn't going to be Quarians, Geth and Rachni.
Children? Nope, they can't contribute to the expedition, so I doubt they'll take them!
Children happen naturally when the infrastructure is in place (and as long as you only select young, healthy people with great training and potential you will have good "breeding stock" without needing to take children from the start...I still hope they go further and take fertilized embryos (!), I mean we make those all the time for science and IVF, so selecting a few thousand of those (who'd normally be thrown away) should not be too hard...and we know that artificial wombs are a thing in Mass Effect, as it's how GRUNT was made and educated (he walked out of the tank a fully educated male Krogan after all!)))
Still, the Salarians would have to send females (otherwise no reproduction!), so I am hoping we'll see more because they can't hide them away on Surkesh (also: I'd love a female Salarian who's not amused with the stereotypes and rebells against being trained as basically a feudal lord and doesn't want anything to do with all of that!)
As for sexual dimorphism:
I'd like for humanity to overcome that (transcend nature) - so I've got no problem with races in Mass Effect not having that in-built inequality (IMHO that's got to go to make both sexes fully equal, same for raising boys and girls differently...no princess treatment for girls and no "soldier-boy" treatment for boys, we aren't in danger of dying out, so stereotypes like male-disposibility have no place in modern society anymore (no more: "Women and Children first" crap!))