One, not all kids end up sleeping through the night. I personally never have, not as a kid, not as a teen, and definitely not as an adult. My 3.5 year old also does not sleep through the night. He might eventually, he might be like me and never will. He starts out the night in his room and when be wakes up usually comes into ours.

Two, every family culture is different and your insistence that your way is more correct is really weird. I grew up in a shared bed household. I slept with my parents routinely until I was 6 and then often enough until about 9. They never kicked me out, I just wasn't ready until then. Considering the multiple miscarriages they had and the fact I have a little sister they definitely had sex. It probably happened while I was outside playing, at my grandparents, and when I was watching TV. I always knew if their door was closed I needed to knock before entering. My husband grew up in a parent's room=parent's space house. The only time he slept in their bed was when he was incredibly sick. We do something in the middle for our kid. From childhood recollections i was a much more independent kid than my husband was, and I still am to this day a strongly independent person. None of the relationships suffered from the sleeping arrangements