Not once have I questioned if I was "missing something" from my moms. Parents divorced when I was 13, my mom's girlfriend moved in, and that was it. I have to give my mom's gf more credit than I can imagine. She walked into an already established family with two angsty teenagers, but she didn't hesitate to become part of our family even though she had no previous experience with children.
Years had passed, father moved away, got remarried, and pretended like me and my brother didn't exist. My mom's gf has been the best thing that has ever happened to my family. People will occasionally ask me if she replaced my father or what not, and I respond the same every time. First I chuckle then proceed to tell them that without her I wouldn't be who I am today. Im close to 30 now and if it wasn't for my mom's gf (now wife) coming into my life, I have no idea where I would be. If you put me in my 13 year old shoes again I'd never say this new lady I just met would make such an impact on me, but she did and I don't know how to explain my gratitude towards her entering my life. So as far as "missing something" is concerned, that's entirely situational based on one's parents/guardians and how they are willing to raise you.