Hey there :p
Even if you go single you can engineer the baby with whoever you can manage to bring in with you be it a townie you think has good genes etc so you can still do it single also you can go guy/guy girl/girl if that is your thing or guy/werewolf girl/fairy etc etc etc no limits
But yes you can bring the child back to the present.You go to the hospital it costs some money (cant remember price but its less than 10k) and then you will get a few customize options like hair and some traits
Remember engineering is not instant like it takes several sim hours so make sure your sim is not having to potty or hungry sleepy etc.
And most importantly have fun with your lab created babies :p like in movies what could go wrong right