remember we werent shown or told all of what happens in the opening, all we know is that you were married w/ wife/husband and child, and 200 yrs pass since you entered the vault. i am thinking cryogenics played some part in it. but we dont know if wife survived and made it out, if baby died/lived. or how many other choices we made while in the vault before going to sleep. i am sure we will have more freedom than the little bit shown of the opening implies. maybe you got the option prior to starting the game and doing the prologue to having 2 guys or 2 girls married to each other, you never know.
look at dragon age and mass effect, ME's generic story line asks you to be a male, and most likely straight, but you still have the option to romance guys or girls. as for dragon age, the first game does have a set story line but it is less scripted and gives you MORE options in weaving your own story, it is DA2 and inquisition that changed it up to be more like ME in have more events/choices scripted. as boring as DA:O is, i love the way you can create your own story and wish that DA2 and DA:I kept that in it. i think it was just too much work to do for bioware so they opted for the more scripted da2 and inquisition games. it doesnt mean they are horrible, but it does make it less replayble. now if DA2 had the option of doing what it did w/ more personal choices as in the first game, i would love that.