I don't think anyone has unlocked the secret of how you are selected for a company. Some say it's random (other than ensuring the right number of females go to each company -- i.e., as a percentage of the total). Others believe there is some attempt to mix perceived qualities -- i.e., don't put all football recruits or strongest h.s. students in same company. They don't put siblings in the same company, far as I know.
It is one thing about which I'd never waste a second of my time b/c -- unless things have changed, there is absolutely nothing you can do about it. You can't select your co. and, if your class is one that changes companies at some point (whether and when this happens varies over time), you don't get a voice in where you go.
I've never heard of USNA -- in modern times at least -- making an effort to place people in a company where family members were assigned. If it happens, my guess is that it's coincidence.
Finally, forget about who's strict and not. First, you can't control where you go and, second, this too can change over time with new Co. Officers and mid leadership.