We let our kids stay up until they went to sleep at their own pace and then they seemed to wake up at a relatively civilized time.
With one kid it isn't too bad, but when you have multiple kids they tend to be up with whomever is the earliest riser, because they make a lot of noise when they get up and wake everybody else.
I'm 33, definitely more of a night owl but if it's sunny out I'm pretty likely to be wide awake at 6am after going to bed at 1. Black out curtains made all the difference for me.
I believe all babies are different, so luckily our first have been kind to us this far with her sleeping habits and mood.
My hypothesis is that all the nonsense about kids needing 12 hours of sleep/"more than adults"/early bedtime is just that, started by parents who wanted some time to themselves at night and perpetuated through convention.
Our kids started sleeping, waking up and generally behaving better once we stopped enforcing arbitrary bedtimes.